I just put a newly modified (cam, intake, aluminum heads, headers....) 455 ci in my stock 1966 Skylark. Originally it had the 300 ci engine. Question: How can I tell what rear diff it currently has and will I need to replace the it? If it needs to be replaced, what is the most common swap?
You most likely have the Buick 8.2 w/a 2.78 gear, at least that is what mine had. A common swap is the 71-2 Skylark 8.5 Buick rear with bolt-in axles. That's what I put in mine with a 3.08 posi behind my 455.
There are parts readily available for the early BOP 8.2. Doesn't need to be replaced. It's got bolt in axles. Just put a Posi and gears in it.