[shadowgray396]

Welcome to the site. Not all SS-optioned Chevelles came with a 12-bolt rear end. The SS Equipment option was available with any optional V8 engine in 1972. The L65 350-2bbl engine came standard with a 10-bolt rear end and only equipped with a 12-bolt rear end when the trailer option (RPO YD1) was ordered. The other 3 optional V8 engines (L48, LS3, and LS5) were outfitted with 12-bolt rear ends so when one of those engines was ordered along with the SS Equipment option a 12-bolt rear end was used. Positraction was still an option; an open rear end was standard. However, a 12-bolt rear end, as well as Positraction, was available on non-SS-optioned Chevelles as well so the presence of a 12-bolt (with or without Positraction) is not an indication of a 1972 SS-optioned Chevelle.