12 Bolt Chevelle rear

I have been searching for the best rear I can afford for my budget, and I have come across a 12 bolt posi rear, cleaned and rebuilt without gears for $400. I have a 1970 Skylark convertible with a fresh 455, and need to learn all I can about putting this Chevy rear into my Buick. Are my gear options any better with the 12 bolt? I already know I can't get 3.42's with an 8.5 or an 8.2. Would I be able to use my Buick wheels on the chevy lug bolt pattern? What other problems might I look out for with this rear? I was at Spring Carlisle this weekend, and did not see a 12 bolt posi rear for under $1200. Thanks -Joe
 
The Chevelle 12 bolt should be a bolt in replacement for your Buick. There are actually 3 different Chevelle 12 bolt rear ends. There is the '65 and '66 12 bolt, which is 60 inches wide overall with flat spring percehs, the '67 Chevelle 12 bolt, which is also 60 inches wide, but has spring perches with a raised center, and there is the '68 to '72 Chevelle 12 bolt, which is 61 inches wide over all with the raised spring perches. You will need the '68 to '72 rear end for your car. There is a chance that your u joint will not be the same size as the Chevelle yoke. You might have to get an adapter u joint to make it fit.
 
12 bolt chevy rear

Being that this 12 bolt comes with 411 gears, what would be the overall gear range available for install? I will be running a 455 Buick, and I am under the impression that 411 gears are great for Chevys, but not Big Buicks. Is it possible to use 3.42's with this rear? Are they readily available if so? Thanks
 
Depends on which series posi is in it. If it has a 3 series then a 3.42 would be no problem. If it has a 4 series then you will need a 3 series. The 3.42 is a very common gear for the 12 bolt now. It was not a factory installed ratio, but the after market is making them.
 
8.5 gears

Why can you not get 3.42 gears for a 8.5 rear? that is th emost common gear for that size diff??? Confused. I have them all day long. Maybe you are confused in the size you need and the rear you need them for. 1967-1970 10 bolt rear gear true you can not find them at all. Only used stuff. 1971 1972 3.42 gears should not be any problem. Jim
 
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