['ol Pinion head]

Need to supply the casting number on the lower webbing of the housing. Is it a 3.90 or 4.33 HD STT rear?

For '70 model Pontiac A-body's & GP 10 bolts, the original housing has different housing end & uses a tapered bearing axle & an external seal, a 712146, outboard of the tapered axle bearing. '69 & earlier A-body's w bolt in axles used a sealed axle bearing, the RW507C & internal axle seal that seats up in the axle tube inboard of the axle bearing. The early sealed axle bearings eventually seize & begin to chew up the axle. With the HD STT 8.2's having there own HD axles, the typical solution is buy a new pair of axles from Moser. If standard duty tapered bearing axles, nice used are out there, I should have several pair.

One thing I like to note, the '70 & later tapered axle bearings, next to never exhibit wear issues. Most get replaced from a tire/wheel getting curbed hard & the axle being bent. For many years in 8.5 A-body rear builds, I replaced the A9 or A10 axle bearings just out of practice/ "all new bearings, races, seals." The last half dozen 8.5 A-body builds I've taken nice used A9 axle bearings that I'd pressed off & along w a new National 712146 seal, carefully replaced both, typically using a new lock collar sourced from a cheap new RW507 bearing box. After robbing the new collar from the box, I throw away the cheap Chinese axle bearing.