My car has an 8.5 O type rear. It's a ten bolt but actually has 12 bolts on the cover. I have a photo of it on my computer at home. Looks almost exactly like the one above but with 12 bolts holding the cover and the two ears sticking out below at the 4 and 8 o'clock postions.
Check this out as well. The best page I've seen for identifying rear ends-
http://www.oldsmobility.com/10bolt-tech.htm