Does anyone know why or when the change of the axle bracket came to play on the Second Design - Rectangular Radius Rod. I've seen two versions, one have a press mark and the other having a hole drilled just above the side dimples? I'm surmising a June of 67 change.
I assume the square was needed to handle the larger engine torque and also the additional snubber bracket added as a means to limit the rears travel due to spring wind. As for a transition period I don't know when. We can only get a rough approximate from the dates within the assembly manual but that's not exact when it hit the production floor.
The two Camaros I have with original rears are one 'BJ' rear (3:07) stamp dated 0404 for a LOS 4B (April 13th per UOIT) dated trim tag and that has the round bar with no holes provisioned for an additional bracket. That car has the L35 w/TH400. The other rear is a 'QK' (3:31) stamp dated 0331 for a NOR 5B dated trim tag and that has the square bar with the additional bracket for the snubber. That car has the L35 w/4 speed.