Hi,
Been doing some research on a 65 442 axle types and it occurred to me funny that Buick used their casting for the 65 Gran Sports
Pontiac GTO 335/360 hp 425 tq range
Olds 442 345 hp 440 tq
Buick Gran Sport 325 hp 445 tq
Fyi: there is 2 types of BOP 10 bolt rear axles
Buick: 2 scallops on cover and 1 horizontal rib on each side
Pontiac: same as above along with a diagonal rib on the passenger side top, 65 only, 66 and later had a diagonal rib on each side.
Oldsmobile used both axle casting depending upon axle ratio, 2.78 Buick, 3.08 Buick or Pontiac and 3.23 up Pontiac as considered stronger.
Olds wagons all got Buick, maybe because of larger wheel bearings like th GS?
Wonder if Buick ever considered using the Pontiac casting for the Gran Sports as they clearly had the highest torque rating?
Regards,