Topic: Are these Undercarriage Factory Markings?

[BTclassics]

First time posting! I'm working on my Mom's 1966 Mustang 2+2 Fastback, original California black plate car (San Jose assembly plant). My family purchased the car in the 1990s sight unseen from California where it had been in storage for a number of years and had it shipped to NY. It is pretty original - all original interior, 1 exterior repaint in the 1970's at the dealer in the original Ivy Green (reason unknown - doesn't even look like they even primered between coats and no sign of any body work), even still has the CA thermactor emissions system on it. It's done well at some judged shows in the past and is still a really nice driver. Last summer the radiator let go so I took it out to be re-cored. While the radiator is out, I thought now is the time to detail the engine compartment. That led to trying to clean up the entire front end!

Under the front end I thought I saw some surface rust poking through the original black undercoating. After using a wire wheel I discovered that it was not surface rust, but a brownish paint/ primer. Everything is solid but the undercoating is coming off in spots. That's when I discovered these yellow paint marks on the driver and passenger side front frame supports. I was curious what they were for.

I'm kind of in a dilemma as I wasn't planning on stripping all the undercoat from the wheel wells, but yet I don't think I want to re-undercoat. (The metal is really clean and the car doesn't get driven in the elements.) So I'm looking for some thoughts on what to do. I don't plan on disassembling any further. I.e. Didn't want to drop the front suspension or pull the engine/ transmission. This was intended as more of a cosmetic freshen rather than full blown restoration project.

Should I try to recreate these paint marks?
While painting everything black would be easier, is it worth doing the proper colors? (I've been looking through this forum and it's a little overwhelming as to what gets painted, left natural, overspray, finishes, hardware, etc.)

[jwc66k]

First, welcome to the Forum.
I found similar numbers on my San Jose Oct 65 build 1966 Mustang GT HP Fastback, but in white. I was told they are rotation numbers, used for correct parts placement. What is your car's scheduled build date? (That's on the door data plate).
Depending on your "restoration" goal, keep them, or try and reproduce them if possible.
Jim

[BTclassics]

Thanks Jim!
October 14, 1965.

I think I'm going to have to repaint either way. The little "white" marks are bare metal where the black paint is coming off. If I had known the paint marks were there, I would have have used a less aggressive method than a coarse pneumatic wire wheel and a metal scraper. On the plus side, the entire car is so clean and solid - not something you see if this was a native Northeast car.

The passenger side is easy to read "331-32". The drivers side looks like 331 X (maybe?) 1. Would both sides be marked by the same person on the assembly line?
Would this area have been undercoated at the factory or was that something done at a dealer?

-Brian

   

[jwc66k]

Brian,
Your car was built one day, a Thursday, before my 66 Hardtop, 15Oct65 (15K) and three days before my 66 GT Fastback (18K). The Hardtop (an "A" code) was a daily driver (and still is). The Fastback only goes out for "special occasions".
Jim

[J_Speegle]

First welcome to the site.

First time posting! .
Under the front end I thought I saw some surface rust poking through the original black undercoating. After using a wire wheel I discovered that it was not surface rust, but a brownish paint/ primer. Everything is solid but the undercoating is coming off in spots. That's when I discovered these yellow paint marks on the driver and passenger side front frame supports. I was curious what they were for.

As a new member get use to trying the search feature as there is a ton of info already here in threads, articles and library. In this way you'll get even more out of your experience with additional findings from other cars built at the same plant around the same time including pictures for you to compare and learn from. Search feature like on most forums will take some time to figure out to get better results but worth it IMO

In short the numbers on the frame identify the hook that each fender that would be installed on your car were hanging when they were being painted

Here is one San Jose frame rail discussion

https://www.concoursmustang.com/forum/index.php?topic=28696.msg170046#msg170046

The X on the drivers side of the frame rail indicates that the steering box bolts have been torqued and checked.

I'm kind of in a dilemma as I wasn't planning on stripping all the undercoat from the wheel wells, but yet I don't think I want to re-undercoat. (The metal is really clean and the car doesn't get driven in the elements.) So I'm looking for some thoughts on what to do. I don't plan on disassembling any further. I.e. Didn't want to drop the front suspension or pull the engine/ transmission. This was intended as more of a cosmetic freshen rather than full blown restoration project.

Should I try to recreate these paint marks?
While painting everything black would be easier, is it worth doing the proper colors? (I've been looking through this forum and it's a little overwhelming as to what gets painted, left natural, overspray, finishes, hardware, etc.)

What it's worth is up to you. Should you retain as much original details?  We'll your asking in the wrong place if you expect anything less than yes  Once these details are erased then they are gone to you or the next owner. IF your just going to put a new paint job on the car I would suggest, and have practiced this, leave the undercarriage alone so that the next person can make their own choice. Of course the car isn't restored but it will serve it's purpose for you.

This is a challenge for owners with what has been referred to by many of us as a "tweener" a car that is part restored and part untouched. Good luck with your choice, you made them 

As a side note remember that the door tag date isn't when the car was built just when San Jose guessed/estimated that it might be completed