hey guys ive got a 66 and right now its got a 10 bolt in it and i am looking at upgrading to something stronger i know that the 68 and later rears are about 1 inch wider (1/2 per side) right ? if thats the case will my control arms bolt into the same places on the rear? the rims i am running are going to need a 1/2 to 1 in spacer to be perfectly centered in the wheel well and i am wondering if i can get a rear from a later chevelle and have it work with no other mods. thanks a million guys
josh

Yes, it will work, but Youl need to make up the difference with wheel offset.

Joshua, the spring perches are a bit different on the 68 and up 12 bolts. They are in the right place but they do not use a bolt and retainer for the spring. They have a cup the springs sits over.
When I upgraded from my 10 bolt to a 12 bolt I found it almost impossible to find a 64-66 12 bolt housing around here. I bought a complete 12 bolt from a 68 with 2.73 open gears for $150.00. I ordered the ford ends from moser and shortened the axle tubes. I then got moser axles with the pressed on bearing. It turned out great and overall cost wasn't that bad.
I should add that I was lucky enough to find a set of used axles (moser 31 spline) from a nova and 4 series carrier on line.

hey guys thanks for the heads up. i have really bad luck with parts that are sposed to be strong enough. ( trashed a built 10 bolt twice in my nova with a mild 350) i called the guy who does my rearend work (pro gear in sandiego) and he said not to mess around trying to build a 10 bolt this time or even a 12 bolt and to go with a s60 dana rear. I had been looking at these for my nova anyways so i think thats exactley what the doctor ordered for the chevelle. The big block is prety tame right now but i beat on stuff HARD and dont care for it when parts break that are sposed to be strong enough.
thank you all for your help i will have them make the rear end the perfect length so it will perfectly center my wheels in the wheel wells.
joshua