Topic: 1968 GT 390 Drive Train Advice Verification

[bullitt68]

I have a GT 390 recently purchased and the motor is not original to the car. Car was built June 5, 1968. Just curious if I should try to find correct date & casting parts or just rebuild the parts I have already and how acceptable that would be. Here are the various parts. I would like to know which parts I should considering replacing and which ones I should restore and use.

Thanks

[67gtasanjose]

If I were in your shoes, and since I am not, it is hard to say what the best choices would be. I didn't see any one item shown that looks "Concours Correct" by date code and in the alternator, starter and carb, looking correct either.
I read in one of your initial posts that you were just "cleaning things up, not striving for Concours" (as in not planning to do a full restoration). The project is all taken apart right now, so now is a good time to get things "right", if ever there was a good time.

If you haven't yet read through the article on Date Codes (found in the Library section of this forum), now would be a good time to do so. You will have a better line of questions afterwards and quite possibly, you will answer many of your own questions on authenticity for your build date.

Then you can decide just how far towards the "numbers matching" Concours Path you wish to go. I was told very early on that few, very few restored cars ever have all numbers matching or only a few restorers even try to build a fully "Thoroughbred Example" because such details are very difficult to get right after so very many years or replacement of wearable items, like the ones you have shown. (Engine transplants, transmission exchanges, rear end changes were VERY common over the years.)

You have a very nice car to work with. It may be very tough to decide what to do now that the "Concours Bug" has bitten you. That being said...if it were me, I would take notes of what you find that has been changed out, restore most if not all of what you already have, begin the hunt for what you wish to replace and continue down the path towards re-assembling the car and perhaps at a later date, once if or ever if you find enough of the correct parts for your build date, do another "freshen-up" to get those details corrected to your liking.

Doing all of that NOW might become overwhelming. Sourcing some of the parts you need might take years and if nothing else, thousands of dollars more than you wish to spend right now. On the flip-side of that, I have found that once you are not "chasing" parts, they seem to show up miraculously out of nowhere at a reasonable price. In any event, if it were me, I would want the car back together again in at very least, a more presentable quality of workmanship, even if some of the finer details are off a bit. That is only my opinion though. Your opinion (and other's opinions) may vary.

[bullitt68]

Thanks Richard. Just after I posted I found the Decoding section and read through it. I found it fascinating ind informative. I think that you are right and will most likely proceed down the path that you have mentioned. I know some local Mustang/Ford guys and will see what parts I can dig up and swap out what I can, but mainly focus on getting the car back together and in a state of good repair. It does appear to me that the engine is a Mut, mixture of parts either combined over the years or put together when the restoration was done. It would be great if any of these parts turned out to be acceptable parts and at least I would know hat is keeper material and what I will try to replace if possible. So far for the non drive train stuff I have been fortunate enough to find some good quality original parts and in most cases I am restoring as many of the original parts as possible. I guess the main things are motor, trans & diff. I was not able to confirm the dates on those parts so I am unclear if those parts are also long gone as the motor obviously is.

[67gtasanjose]

Thanks Richard. Just after I posted I found the Decoding section and read through it. I found it fascinating ind informative. I think that you are right and will most likely proceed down the path that you have mentioned. I know some local Mustang/Ford guys and will see what parts I can dig up and swap out what I can, but mainly focus on getting the car back together and in a state of good repair. It does appear to me that the engine is a Mut, mixture of parts either combined over the years or put together when the restoration was done. It would be great if any of these parts turned out to be acceptable parts and at least I would know hat is keeper material and what I will try to replace if possible. So far for the non drive train stuff I have been fortunate enough to find some good quality original parts and in most cases I am restoring as many of the original parts as possible. I guess the main things are motor, trans & diff. I was not able to confirm the dates on those parts so I am unclear if those parts are also long gone as the motor obviously is.

You might be surprised what you can "Trade Up To" with the "WRONG" parts on your car. Others may need the particular "wrong part" and they could know of or perhaps help you locate the "RIGHT" part for your build information. I'd say start some "TRADE" listings on a few forums but be very careful too! People in the forums are not ALL nice guys! Check any would-be help out thoroughly if you choose to try and trade parts. So far, I've had absolutely no issues with anyone here on this forum.

[bullitt68]

Great idea. Thanks Richard I will do that

[J_Speegle]

I would take inventory as you apparently already have started doing. Identify which parts can be easily changed out later if need be (dist, carb, exhaust manifolds for an example) and which would be much more difficult (engine block, bellhousing ...)

Set a time period that fits inside your "window" for the rebuild and try and find better dated items where you need for all of the parts while trying a little harder on those parts that would be difficult to replace once the car is together. Think you get the idea.

Might find the "hunt" enjoyable and satisfying when it works out. Sometimes frustrating but with luck and effort you will increase your odds allot

Good luck

[bullitt68]

I would take inventory as you apparently already have started doing. Identify which parts can be easily changed out later if need be (dist, carb, exhaust manifolds for an example) and which would be much more difficult (engine block, bellhousing ...)

Set a time period that fits inside your "window" for the rebuild and try and find better dated items where you need for all of the parts while trying a little harder on those parts that would be difficult to replace once the car is together. Think you get the idea.

Might find the "hunt" enjoyable and satisfying when it works out. Sometimes frustrating but with luck and effort you will increase your odds allot

Good luck

Thanks Jeff. Part of the fun in the hobby for me is the "Hunt" and the research and learning. I think my plan will be to see if I can dig anything up in the next short while and then find a suitable block to start with and build a motor on a stand and take my time. Once it is complete and correct I would just pull out the current motor and do a drop in swap with a fully detailed correct unit. Then I can sell my current motor and not have to worry about how long it will take and I can drive and enjoy my car. Where should I post the parts I am looking to trade up or sell

[bullitt68]

Still not sure if my Diff, trans, alternator, starter, distributor, & water pump date codes fall with the time frame for my car

[RoyceP]

The distributor, water pump, and rear center chunk are all dated wrong for your vehicle. All must have been replaced over the years. Some are also wrong casting numbers, for example the water pump is a C6 casting number which should be a C8.

I don't see a date code for the transmission anywhere.

Still not sure if my Diff, trans, alternator, starter, distributor, & water pump date codes fall with the time frame for my car

[bullitt68]

The distributor, water pump, and rear center chunk are all dated wrong for your vehicle. All must have been replaced over the years. Some are also wrong casting numbers, for example the water pump is a C6 casting number which should be a C8.

I don't see a date code for the transmission anywhere.

Thanks Royce. Where should I find the date code on the transmission? Pretty sure I took photos of all the stamps and castings. I think that the transmission is the correct trans for the car, according to the tag, not sure about the diff. I did notice that several parts on my car including the heads are C6, indicating 1966 year. Starter is a C5 I believe and I have no idea what I am looking fora on the alternators. The Distributor did not come with my car as it had an after market Mallory Electronic unit when I bought the car.

[krelboyne]

Look for the VIN stamp on the transmission.

Since your third member is wrong, I would also double check that the axle housing is a 1968 piece. Probably is, but worth checking.

Your cylinder heads also look like they have been drilled for CJ exhaust manifolds? 390GT heads as far as I know all had 14 bolt holes, your set looks like they have 16 holes?

[70cj428]

I'd look for the partial VIN stamped on the top of the trans ear, It could very well be the original transmission.

If I were you ......

I'd look for a correct dated block and pair of heads and then spend the money to have them rebuilt. The parts you need are not that hard to find as they made a ton of 68 fords with 390's in 68 and the cost to rebuild the engine is way more than the cost of a block and heads as cores. It would be foolish (in my opinion ) to sink a ton of money in parts that you may not be happy with down the road. What adds up cost wise is all the little things that you'll need to scare up to finish the build. Since you have a 68, your car shares some parts with the 428CJ crowd, so you'll be competing with the 428 and KR Shelby guys for some stuff like the distributor, alternator brackets, smog stuff, shifter, ect.

The carb for your car is unique to a 68 390 4 speed car, but the are around, and finding one with the correct date shouldn't be too hard unless you have a real early car. The distributor is the same for a 68 1/2 428 CJ Mustang or KR so that will cost you some cash. generally around $400-$700.

As for the small stuff like the starter, I'd use what you have now, and if you come across the correct one later it's easy to switch out.

As for the bell housing, I'd find a correct dated one, as it's kind of a hassle to switch, and you should be able to recoup most of the money you spend by selling your old one.

Good luck with your project....

John
 

[bullitt68]

Look for the VIN stamp on the transmission.

Since your third member is wrong, I would also double check that the axle housing is a 1968 piece. Probably is, but worth checking.

Your cylinder heads also look like they have been drilled for CJ exhaust manifolds? 390GT heads as far as I know all had 14 bolt holes, your set looks like they have 16 holes?

Third Member? Is that the pumpkin? Sorry I am new to Mustang world. Yes I figured that the heads had been drilled since there are 18 holes instead of 14. So far I have not seen a vin on the trans, but like with most parts on this car there is a lot of paint that needs to be removed. I get the feeling that most everything drive train related has been changed at some point

[J_Speegle]

Thanks Royce. Where should I find the date code on the transmission?

C5 main cases it's following the engineering number on the drivers side of the main case right side up and on C8 cases its on the passenger side up side down




Tailshaft housing engineer and casting date of the part






Don't recall (no pictures handy) if San Jose stamped the VIN on the transmission flange or on the pad on the bottom

I did notice that several parts on my car including the heads are C6, indicating 1966 year.

Don't let engineering or part numbers sway your decisions - that is only part of the puzzle.

Starter is a C5 I believe and I have no idea what I am looking fora on the alternators.

Starter would have an engineering number stamped into the metal of the main case and a date by the time your car got built. 



For the alternator no numbers stamped into the case but is about the style of the case (correct for the cars period)  and it was identified/marked with an ink stamp so if you find the right case its easy to make it look like the original one with the right details. 

Third Member? Is that the pumpkin? Sorry I am new to Mustang world. Yes I figured that the heads had been drilled since there are 18 holes instead of 14.

Not so much a Mustang of Ford think but IMHO a regional thing. Pumpkin = 3rd member (term I use) = chunk - pig = ........

The C7 Heads didn't come with only 14 holes and the C8 heads you will need came in many different exhaust manifold bolt patterns


Will be moving the discussion/thread since we're moving away from general (applies to many years and models) to more year and application focused details.

[bullitt68]

I'd look for the partial VIN stamped on the top of the trans ear, It could very well be the original transmission.

If I were you ......

I'd look for a correct dated block and pair of heads and then spend the money to have them rebuilt. The parts you need are not that hard to find as they made a ton of 68 fords with 390's in 68 and the cost to rebuild the engine is way more than the cost of a block and heads as cores. It would be foolish (in my opinion ) to sink a ton of money in parts that you may not be happy with down the road. What adds up cost wise is all the little things that you'll need to scare up to finish the build. Since you have a 68, your car shares some parts with the 428CJ crowd, so you'll be competing with the 428 and KR Shelby guys for some stuff like the distributor, alternator brackets, smog stuff, shifter, ect.

The carb for your car is unique to a 68 390 4 speed car, but the are around, and finding one with the correct date shouldn't be too hard unless you have a real early car. The distributor is the same for a 68 1/2 428 CJ Mustang or KR so that will cost you some cash. generally around $400-$700.

As for the small stuff like the starter, I'd use what you have now, and if you come across the correct one later it's easy to switch out.

As for the bell housing, I'd find a correct dated one, as it's kind of a hassle to switch, and you should be able to recoup most of the money you spend by selling your old one.

Good luck with your project....

John

Thanks John that is great advice. What section should I start a post looking for parts and offering up any of my desirable parts. Alternator didn't seem to have any dates or part numbers on it. I got the polished version with the car and an alternator and starter from a friend who had some extra parts left over from his 1968 Shelby restoration