['ol Pinion head]

Def, one of the two different versions of 8.5 A-body housings that Olds mfg for '71-72 Olds & Buick A-body's. Buick manufactured the style with the cutout rear cover AND the large totally squared off lugs on the bottom.

Since the early 90's have purchased near 350 8.5 A-body cores for performance rear builds, the Olds mfg style with the A10 axle bearings has always been the least common to pull.

The Olds axle plant, for some reason, also manufactured quite a few 8.5 A-body A9 axle bearing end housings with the same round cover housing. Am starting to pay attention to casting dates on that particular style housing, trying to determine if only manufactured towards the end of the '72 production run.

By far the Buick style center housing (2 plug welds visible outboard per side, as well as the cutout rear cover) is the most common of the '71-72 8.5 A-body housings. Inventory files notes I have 21 of the Buick style & only two of the Olds style.