IF its the same as the '78 to '88 Monte its a g-body frame.
The wheelbase is 108 inches, which is 8 inches SHORTER than a '49 1/2-ton.
Its a perimeter type frame instead of the ladder type originally under the truck. This means the rails bend outward between the axles, and at the cowl the frame is WIDER than floor of the truck.
The front track width is about perfect for an AD truck.
The rear track is a little narrow for an AD truck. In fact using wheels with no offset the bed would need to be tubbed to make room for the tires.
These frames will take most any GM motor, so it could have a Pontiac 400 in it, or even a Cadillac 500, which I've been told is a popular swap, but a US made version came with a 305 or maybe a V-6.
I would say its a BAD candidate unless you are prepared to do a lot of work...
And I'm in the process of using that frame on one of mine, so while I'm telling you its not a good idea, I'm also doing it myself. I'm three years into the project and might be another couple from driving it.
