Your brothers for sure, not sure about yours without seeing the full body shot. But I'm sure it is, since it came with the Chevy motor. One way to know for sure. Look at the frame right in the middle. If the frame is a big heavy X frame with a center bearing support for the driveshaft. Then it is the narrower Chevy frame. The Pontiac frame would be a perimeter frame. Meaning, the frame would kick outwards (a 90 degree outward turn) right at the firewall and run right behind the rocker panels. Then it kicks back in right in front of the rear tires.
Correct. The true wide body US Pontiac frame uses a perimeter frame, so there is no X down the middle, and the perimeter frame uses a long, one piece driveshaft. So you definitely have the Chevy frame too. Which means it has the weaker Chevy 10 bolt Hotchkiss style drop out center section rear differential. The Pontiacs had a much stronger rear differential. The Pontiac rears were even used on early dragsters because they were so strong.
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