Sort of looks like an 8.5 10 bolt with that corner lug off the bottom of the rear. One of the numbers on the tag says 2.41, could that be the ratio?
Not sure but it does do the infamous cherp of the tires in a parking garage so it might have a "posi" or LSD im just to lazy to check
More then likely a 2.41. But really need a better pic to tell if 8.5. I think it’s alittle small. So possibly a 7.5.
99% sure that's a 8.5 with a 2.41 gear. They would have never used a 7.5" in a big car, they were used in small stuff like Skyhawk's, Vega's and such.
Measure the cover. From the link I posted, https://www.onedirt.com/tech/drivetrain/10-bolt-chevy/ 7.5-Inch "Although the 7.5-inch 10-bolt closely resembles the 8.5-inch housing, you can positively identify the Chevy 7.5-inch rearend by measuring it. The oval-shaped cover measures 8 5/16 inches by 10 9/16 inches. The distance between the bottom center bolt in the cover and its adjacent bolts is 3 1/4 inches. Inside, the ring-gear bolts are the same as the 8.5 corporate unit, but the pinion-shaft diameter measures 1.438 inches. Like most 10-bolts, the axles are held in place by C-clips on the inner end of the axles."
Ya but just as u said it tho Chevrolet has a different cover and the internal design is completely different
I can't tell from your pictures. You need a clear picture of the rear cover, and the rear u joint attachment to the yoke. Get that Buick in the air and takes some clear pictures.
The u joint, is it attached with u bolts and nuts, or straps and cap screws? It sure looks like an 8.5. Monzaz or Brian Trick should be able to tell you for sure.