Topic: 67 SJ Running Change Survey - 67 Main Floor Differences

[J_Speegle]

Often some of us keep a few details to ourselves so that they can be used to help determine original from rebuilt cars or even real verses fakes or rebodies. When I ran across this detail, during a somewhat recent study of a car and looking for data and discussing it with a few others, I felt it was better to share this with the community so that restorers would hopefully make better choices when choosing replacement floors for their rusty projects and since it is such a visible feature judges would be aware of it and act accordingly. Some may not be happy with my decision to share but felt this was the right course in this situation.

What am I referring to is a change in the main floor stamping pattern between earlier and later Mustangs and Shelby's. So far this differences include two pretty visible and quickly noticeable areas.

First at the front of the floor pan directly behind where the front frame rail attachment point end we have two  pairs of ribs formed into the panel for straight and rigidity. The first pair are straight on earlier cars as they were in 65-66 floors.  On the later cars the first rib in that first pair was reshaped into somewhat of a T for additional support and rigidity. Both styles are shown in the picture below. Top example is the earlier version - lower the later.




At the rear of the same panel in the raised (rear seat platform) section an addition rib was added to the later floors (appears to be have been included at the same time as the forward change) at a slight angle near the corner bend in the panel as shown below. Top example is the earlier version - lower the later.





Hope this helps others when making choices for their cars and projects.

Currently I'm going through data to try and figure out the possible change over range for the plants I can. San Jose will be the easiest since we have allot more data (real build dates) than other plants

[67gtasanjose]

My 11/2/66 SJ built is early design on both changes...but you already knew that since the pictures provided look mighty familiar!

[Shawn]

Hi Jeff,

I'm checking my 67 tomorrow for the stamping differences you identified here.  I'm assuming (if I have late 67 version) anything later 67 - 68 with this stamping is accurate?  If earlier without the later additional stamping will 65 - early 67 be accurate?  My car was made 4/67 in NJ so were there plant differences in the floor stamping other than what your identifying. If I'm lucky enough to find a properly dated floor where are the stamping(s) located? I'll report back soon with my floor markings


Thanks for the OP and the pictures are a huge help !

[Shawn]

My NJ built 4.11.67 has the reinforcement stamping at the front and not the rear.

My San Jose built 4.10.67 has the reinforcement at the front and not the rear.

I cannot locate the date stamps both are original floors.  Any idea on where to look?

[67gta289]

Mine is early also.  December 20, 1966

[J_Speegle]

I cannot locate the date stamps both are original floors.  Any idea on where to look?

Typically at the rear edge of the main floor panel on the passenger side. Maybe one inch in from the edge or slightly more. Often covered by a wide flat application of seam sealer

Typical sheet metal dating pattern was used

An example

[J_Speegle]

My San Jose built 4.10.67 has the reinforcement at the front and not the rear.

That is a odd one that I didn't pick up originally when I first started this thread. Will need to add it to the progression. Looks like that version may have been used for a few weeks before someone caught the detail or an engineer wanted more support

Would be very interesting in your floors stamping date since that is even better than the cars real build date for this sort of thing