I went to pick up my frame from the company I had powder coat it. (it looks ridiculously awesome btw)
And the owner of the shop told me he had a frame very similar to mine that he wanted to find out what car it's for. So I went out and showed him the vin stamp on the frame. It looks very similar to mine but the frame horns are different. It's tubed on the front and has a flange with four bolt holes on the end of each frame horn. I wish that I had my phone with me for photos but it wasn't to be. Anyway the stamp is 6RR700691. Any help?

 

Mine is 7z###### which means 67 Fremont car. So I figured 66 but what's the RR?

 

The first character of the VIN derivative is the same as the first character of the VIN, which would be a "3" for an Oldsmobile Division car (1 for Chevy, 2 for Pontiac, 4 for Buick, 5 is GMC, 6 is Caddy, and 7 is GM of Canada). The second character is the year of manufacture. The third character is the assembly plant. "Z" is Fremont, "R" is Arlington, TX. The last six are the build sequence number, same as the last six on the VIN.

In the case of your Fremont car, you appear to be missing the first character. The VIN derivative is a nine character number and you are only showing eight.

As far as the unknown frame is concerned, if you are reading the VIN derivative correctly, the "6" in the first position would indicate Cadillac. GM started using letters for the year in the early 1980s. "R" in the second position would indicate the 1994 model year. "R" in the third position would indicate Arlington, TX. The only 1994 Cadillacs with a full frame were the Fleetwoods, and I don't know if those were built in Arlington or not. This is a case of needing to verify the VIN derivative.

Edit: I just reread your initial post. The flanges with four bolts on each frame horn are for the hydraulic cylinders for the 5 MPH bumpers, so that would indicate a 1974-newer frame (still consistent with a 94 Fleetwood).

 

I believe the last couple of years of full size RWD Chev/Buick/Cad production was exclusively assembled at Arlington.

Henry

 

So there ya go. Mystery solved.

 

20140815_194205.jpg
Here's a photo of my stamp.

 

Well, that didn't help. It's rather blurry. It's only 8 numbers long. 7z103857. Weird.

 

By the way, thanks for the help guys.