Topic: Part Numbers verses model years?

[KevinK]

Is there a clear understanding how part numbers or engineering numbers transitioned from year to year?  I saw a post about a 79 model with mostly D9 part numbers on the engine but the intake was an E0 number.  Clearly new parts did not just show up on January first every year.  Did they even show up on Job 1 for the new model year in August?  Is the only option to decode the manufacturer date on the part?  Thanks for the input.

[67gta289]

When it comes to Ford part numbers, the first rule of thumb is that there are always exceptions.

By far the most typical scenario is that the number is assigned at the front end - during the budgeting and design phase.  There is a target model year, a vehicle (program) the part is funded by, and the responsible department.  This makes up the prefix.  Next is the basic part number, which only gets interesting when some new gizmo is in play.  The suffix can represent either a revision or a variation (such as color).

I would expect that all of the parts used on a 1979 Mustang would be D9 or earlier.  Earlier because there is huge cost savings with a "carry over" part.  With a carry over, there is no budget, and no increased cost.  Would a D8 Mustang fender carry over to a D9?  Obviously not.  But would a D8 2.3L engine air cleaner carry over? Very likely.  In fact, the air cleaner would more likely have been carried over from even earlier.  The point is that at the beginning of a new model year, carry over parts do not get a new prefix.

Cross over (from another platform) is also something to consider.  A radio knob designed for a 1977 Grenada might have been perfectly fine for the 1979 Mustang, so it would carry the D7 Grenada (D7D*) prefix.

When might an E0 part shown up on a 79 Mustang?  I can think of a couple potentials; (1) at some point after the 1979 models were out, a problem was uncovered, something that was perhaps a recall situation.  If a new part would need to be engineered, since it would also be used on the 1980 model, the option would be to retain the D9 part number and change the suffix revision letter, or to go ahead and switch it up to an E0 prefix.  This is somewhat of a judgement call, both would work, technically.  The call might have been made based on accounting or legal purposes.  (2) there might have been a new feature that was ready to go for the next model year, but there was a potential sales advantage to release it ahead of time and not wait.  But the design was for the next model year and would therefore carry those numbers.

Keep in mind that the last paragraph is speculation.

To repeat all of this in a few words - there was no engineering part number transition from year to year.

[jwc66k]

What's missing from this thread is that Ford Motor Company had two different part numbers for the same part. Well, not really. The assembly line used "engineering numbers". With this "engineering number", parts, and sub-assemblies, were designed, identified, purchased, received, inspected, inventoried, stocked, distributed and ultimately found their way to an appropriate vehicle. The "engineering number" document specified just about everything, dimensions, materials, finishes, inspection criteria and most important - who the manufacturer was. This documentation practice was a dual edged sword. It actually reduced paperwork in purchasing, inspection and inventory. One piece of paper "fit all". If a second (or more) vendor was used, a different "engineering number" was created. One "part", two "sources". This "practice did not happen often.
For vehicle service at a dealership, Ford used a slightly different number, a "service number", best described as a "stock number" or "inventory number". It was also a "looser" form of document. The "service number" actually referred back to an original Ford "engineering number", but often included additional "purchasing" (quantity in the bag), "inventory" (where to stock the item) and additional "engineering" requirements (finish being one).
The bottom line is - when you refer to any Ford Motor Company part number in discussion, like "for sale" or a "search for" (wanted), include the first FOUR characters of that Ford number. It makes a big difference.
Jim
One more "thing" - Exceptions are normal.

[KevinK]

I understand most the the Ford numbering system. Let me make it simpler. 

For a 67 mustang, at what point (date) would it be acceptable to find a C8xx part number on the intake of a standard production built engine?

[jwc66k]

I understand most the the Ford numbering system. Let me make it simpler. 

For a 67 mustang, at what point (date) would it be acceptable to find a C8xx part number on the intake of a standard production built engine?

Just for reference, what engine, what date code on the intake, the engine assembly date and the Marti build date of the car? Remember, engines were not built at the three Mustang assembly plants.
Jim

[CharlesTurner]

I understand most the the Ford numbering system. Let me make it simpler. 

For a 67 mustang, at what point (date) would it be acceptable to find a C8xx part number on the intake of a standard production built engine?

It has to do with specific engineering changes and I wouldn't say there is a general rule.  There were '65 Mustangs built in May of '65 with C6OE 4V intake manifolds.

[rockhouse66]

I understand most the the Ford numbering system. Let me make it simpler. 

For a 67 mustang, at what point (date) would it be acceptable to find a C8xx part number on the intake of a standard production built engine?

I would think the date code on the manifold would answer your question.  If the date on the manifold is earlier than the build date of the car I would think the C8 number would be okay.

[KevinK]

Thanks for all the info.  Further details shows the car was a July 79 build date.  Having an E0 part on the car seems very possible.  There was also the possibility of the Hi Altitude package may affect the engine build but does not show up in the MPC.  In this case, we were discussing an intake manifold.  The MPC had no separate listing.

[67gta289]

Thanks for all the info.  Further details shows the car was a July 79 build date.  Having an E0 part on the car seems very possible.  There was also the possibility of the Hi Altitude package may affect the engine build but does not show up in the MPC.  In this case, we were discussing an intake manifold.  The MPC had no separate listing.

Two comments on this one; (1) the E0 part number, assuming we are talking about what is commonly referred to as the engineering or casting part number, does not necessarily equate to an E0 prefixed service part number, which would affect what is listed in the MPC, and (2) if the high altitude package required a different intake manifold, I would find it very hard to think that Ford would omit this from service.

I would not have any heartburn about an E0 part on a July build.  Is this a 4, 6, or 8 cyl?

Attached is the 1979 MPC info, which I assume you have, and the 1980 as well, which you might not.  The before 4/81 replacement on the 4.2L (255) with an E1SZ-9433-C is interesting, noting the shift from basic part number 9424 to 9433.  9433 is the basic part number for the gasket set, so I would write this off as a typographical error.