['ol Pinion head]

The rears in '65-70 US built big Pontiacs are P series 8 7/8" rears.
You will need to find someone who has a clean loose housing or rear to have the outer shock/lower control arms removed from. Have cut the last 15" off many an early 8.2 A-body housing to later remove the outer brackets for use. Unfortunately, don't buy '69 & '70 Bonne's as partscars anymore & am out of housing ends for these. The housings for the '65-70 P series rearends are divided into early & late styles as far as bracket mtg goes. As long as you stick to an original P series rear for donor brackets from a '68-70 B series Pontiac, you should be fine. Upper control arm mounts will have to fabricated...typical course of action on 9" housing swaps.