10-Bolt I.D.
Since there are a few choices of rear axle to be found under the GM cars we're covering in this story, here's a quick visual reference to help figure out what you're looking at the next time you go to the boneyard.
GM 8.5-inch 10-boltThis is what you're looking for if you want to replicate our efforts. The 8.5-inch axle went into service in most '71 car lines, but don't make assumptions as it wasn't always the sole choice. The smooth, round cover with 10 bolts narrows it down, but the 8.2-inch housing is very similar. We think the best tip-off are the angular casting "ears" seen in the four and eight o'clock positions of the housing. We haven't seen these on any of the 8.2-inch rears we referenced; all of the 8.5s we checked, including some for other applications, seem to have them. | 
Chevrolet 8.2-inch 10-boltThis is the rear you're most likely to find under a first-generation Camaro, since the only other rear the factory used in these cars was the coveted 12-bolt. Look for a round cover with 10 bolts and a lube "gutter" similar to a 12-bolt. Note the lack of the angular casting "ears" found on the 8.5-inch version. |
B.O.P. 8.2-inch 10-boltThis axle would probably only turn up in a '67-'69 Firebird, but after all these years, who knows what swapping has gone on before you got there. It still has ten bolts in the cover, but note the two cutouts in the nine and three o'clock positions. The B.O.P. rear also uses flanged axle retention, rather than the C-clips used on the other two assemblies. | |