While at the BG Nats this year I enjoyed examining the completed big block chassis (without the body) on display with the concourse cars. It was for a hardtop GS and had open frame rails. I mentioned to the owner (sorry, forgot his name) that my ‘70 GS455 hardtop has a boxed frame that I had a hard time running 1/2 inch fuel lines through to feed my fuel hungry stroker motor. He mentioned that only convertible cars received boxed frame rails and my frame couldn’t be original. Since my car has Sloan documentation and I have all the restoration receipts I’m 99% sure the frame is original. He showed me a place on the frame where I could see the partial VIN stamped. So, can it be seen without raising the body? (Which I’m not about to do) Also has anyone else discovered a boxed frame under an original GS hardtop?
Ray, if it has not been cut and welded back in you can also do a quick check on the frame number and date. It is just in front of the rear bumper bracket on the driver side. .
Thanks, I'll take a look. How do I decode that date? And, if it's date coded for my build, how do I tell if it was born with my car?
8-6-71 1st shift. I have never seen an original 70-72 GS Coupe with a boxed frame, however I have boxed a few coupe frames myself in the past with pieces taken off original convertible frames, Between the boxed frames and the coupe bodies it makes them a lot more rigid. It’s an old racer’s trick around here. Post the part number of the frame and the letter codes and date here and we can figure it out. Duane
It's Memorial Day weekend so, I'll have the car up on a rack later this week and will post back then.
Ray, you were talking to me, the pics you posted are of my 70 GSX Stage 1 4 speed chassis I had at GS Nats. As we had discussed, there was no Heavy Duty frame option for 1970 GS hard top cars. However, Pontiac GTO's in 1970 could be ordered with a Heavy Duty frame option on 1970 GTO / Judge hardtops and you received a convertible frame. As I had told you, get the the make and stamped date of your frame, should be XE which is just a standard 1970 GM A body convertible frame. If it checks out to be a XE frame with a date preceding the cowl build date of your car than maybe it is factory installed?
Thanks Rich and sorry I forgot your name. Is the frame number on the bottom of the frame, the rear edge, or on one side or the other?
I would assume that any car that has been restored, and has a box frame, (and is not a ragtop) was treated to an "upgrade" by the restorer.. or some previous owner. Pictures would help for sure, as Duane said, the factory ragtop boxed frames are very specific in appearance. Only the presence of the VIN number stamped on to the top rail of the frame would indicated the factory built it. Other numbers and date codes can rule it in or out as a possibility, but the VIN would be the only definitive information. JW
Not to sidetrack this thread, but I was under the impression that the crossmember was natural, not black
Well, I took a closer look at my frame and it's open, not boxed. The only area where its enclosed is where it goes over the axles. So, case closed.
Ray, when I was dealing with the Vin altered '70 I was able to find the frame vin with a flashlight and a small dental mirror. There is space enough between the body and frame to do this. IIRC, the vin is under the driver's seat, just forward of the rear mounting stud of the seat. Troy
Here's an example off a '70 Flint Hardtop. Not sure how typical the location is, but this one is about 8-10" behind the center body mount. Was kind of hard to see w/o cleaning the area up.
First thing I would check is the frame numbers in the area that I posted. If they are for a 70 with the correct date then look for your VIN. It is a easy place to see.
