The 69 to 72 Grand Prix frame..
 

I found out an interesting thing about the 69 to 72 Pontiac grand Prix.. The 69-72 GP and the 68 to 72 Chevrolet el Camino both share the same frame. The A.O. Smith 1942 frame.
This frame is massive. I always wondered why the el Camino and the GP from these years were always my favorite handling car.
John DeLorean must of battelled to get to use that Chevrolet frame.. I'll never forget driving the 70 GP for the first time. It had a 455 th400. Wow what a car!! It was fast but just as importantly, that car handled just as good as any of the Mercedes, BMW or other euro cruisers of the day..

I bought a 69 el Camino three years ago. I love this car, its everything I always wanted. Now its time to look for a 69-72 GP.. That car was always one of my favorites.. The interiors of those cars are so beautiful...

Just wanting to brake they ice on here.. This is the reason I signed up for this forum... thank you..

Unfortunately, not true.

'68 & 69 & '70-72 Elco's have a 116" wheelbase.

'69 & 70-72 GrandPrixs have a 118" wheelbase

Have frames of each style, have parted to the ground several dozen ElCo's & GP's of this era.

One of my favorite Elco partscars rolled into a local crusher yard one morning in the mid 90's while I was picking up a '71 Skylark. Still have the GM cowl induction hood that was on that Elco, it had amid scrape on the domed area that needed to be metal finished. Was not a '70 SS Elco, but had been a 350 4bbl car (had a 2.73 12 bolt in it).

Many of those 'Camino frames were carved up for stock cars or had the tails bobbed for convertibles. They are valuable!

are one of those frames pictured supposed to be a Gp? just looking at the placement of engine stands, neither look Gp to me.

best of luck on your Gp quest. hope you find what you're looking for, and don't forget to share the find with us.;):D

Correct, neither one of those frames are GP frames, The engines are much further back. The exact reason I choose a GP over an A body for a stock car basis is engine placement. I raced 69-70 GPs at the local dirt track for 4 years (third picture in my signature picture, is a 69 SJ GP)

. I parted at least 3 of them apart for parts for the race car during that time, and yes they are 118 inch wheel base cars. The only thing that may be close in chevy, is Monte Carlo, but Monte Carlo was 116 inches, not 118 inches, not a direct replacement for GP. Maybe that's the chassis you're thinking about that interchanges with El Camino.

The 69 and 70 chassis have different motor mount stands as there was the changeover from the 2 bolt motor mounts, to the 3 hole motor mounts in 1970. 1969 mounts are welded to the frame, not bolted on as most GM stands are. 1970, I can't recall for sure if they were bolted, or welded to the frame. it's been been over 40 years ago that I raced a GP stock car, that detail escapes me at this date. I don't think any other GM frame interchanges with 69-72 GP.

There were basically 8 frames for the 68-72 A-G bodies (I’m not counting slight differences from year to year or divisions):

1... two door coupe or hardtop, 112” wheelbase, unboxed with short rear overhang (the hardtop version had some heavier gauge sections than post coupe)
2...convertible 2 door, same 112” wheelbase, boxed with short rear overhang
3... four door hardtops and sedans, 116” wheelbase, unboxed with short rear overhang (the hardtop version had some heavier gauge sections than the sedan)
4... regular wagons, 116” wheelbase, unboxed, with long (6” extra) rear overhang
5... “vista” wagons, 121” wheelbase, unboxed, with long (6” extra) rear overhang
6... El Camino, 116” wheelbase, boxed, long (6” extra) rear overhang frame
7... Monte Carlo, 116” wheelbase, unboxed, short rear overhang (difference from frames 1-6 is mounting points for cowl are 4” further back from front axle)
8... Grand Prix, 118” wheelbase, boxed, short rear overhang (difference from frames 1-6 is mounting points for cowl are 6” further back from front axle)

Note:

Frames #7 and #8 are unique because the distance between the front suspension centerline and the cowl mounting point is greater by 4 and 6” respectively compared to all the other frames (1 to 6) that all had the same standard distance from front axle to cowl.

The only interchanges possible:
#1 and #2 in that a convertible frame will bolt into a coupe or 2 dr hardtop (the convertible frame was an option on two door coupes and hardtops usually as part of towing package)
#4 and #6 interchange (though not offered by the factory as an option)

.....No difference in gauges of metal on '70, 71, or 72 2door hardtop frames compared to same year 2 door Coupe frames. Have had numerous frames out of each year, both body styles & two letter frame code & part number was the same for each year. Where one gets into different frame codes on the non boxed 112" 70-72 frames is with factory 455 cars.

'68's & '69's....
Have had litterally well over 150 '68-72 2 door GM A-body partscars. Have only had a few '68 & 69 Chevelle 300 & F-85 2 door Coupes, & usually not at the same time as had '68 & 69 2 door hardtop frames. Not remembering any difference & have sold a bunch of 2 door frames to picky code oriented folks.

I messed up my copy paste when writing my previous post about the 2 doors but the 4 door hardtop frames are definitely heavier (but still not boxed) as compared to the 4 door sedan. Further evidence of this is that you could order a HD frame option on the 4 door sedan and it had the same part number as the standard 4 dr hardtop frame.

As for the two door post coupes I’ll have to look them up in my MPC at work unless someone here beats me to it.

As I mentioned I’m not counting the minor variances from year to year or by division on things like specific engine or differential mounting or brake hardware etc

Bringing this thread back up…

Are the boxing channels of a ‘69-72 GP frame the same as convertible A body?

I have a chance to buy a GP frame and would like to cut the inner channels out for an A body project.

Nate

While they might look similar the GP frame boxing plates are longer front to back because they are 6” longer to account for the front suspension being 6” farther forward than an A body two door frame.