Best I can tell (based on all the ones we’ve tracked), the metal brackets that place the bumper in the approximate correct position come in two basic shapes. The earlier shape is squared and the later is slanted and notched. They both apparently come in different depths depending on the application.
The later style you see frequently listed on ebay for 68-70 big blocks and Boss cars is approx 3 1/4" deep and has the C9 bumper. I still have the one that was on the 70 Boss2 I used to own so I believe this to be correct.
When I started my search, I bought a notched/C9 setup that was advertised as correct for a HiPo. Once it came in with the C9 bumper and I realized it was the same as the Boss2 one, I decided to do some research and ask some questions.
I was told the square version with a C3 bumper is correct. Some rear end pictures of cars for sale on ebay seemed to confirm the square shape. I bought a pumpkin off a 67 S-code car (dated 6M) with the square bracket that is 3 1/4" deep. A later rear end listed on auction referenced a 2 5/8” bracket, which led me to ask a couple of members to measure theirs. Both measured approx 2 5/8”
So my understanding is, based on discussions with some of our members and research from what we’ve tracked, the correct ones for the 65-66 HiPo are squared and approx 2 5/8" deep.
I've since bought a complete 65 rear, a 66 dated pumpkin with C4 equalock/3.5 gears, and a 65 pumpkin dated with open 3.5 gears all having the 2 5/8" square bracket with C3 bumpers. The one on the complete 65 rear was slightly different with only one step while the other two had an extra slight step at the very bottom.
Ending up with extras, I cleaned and sold the ones I didn’t need.
Any other thoughts/comments/corrections?
