Make sure the chevy rearend you have now is not a 12 Bolt, or an 8.5" 10 bolt, If it is just put a posi unit in it, Here is a web site with info about the rearends http://www.novaresource.org/axle.htm
The 8.5" 10 bolt didn't come out until 72 , so if your looking to change the rear end look for one from the different cars that oldskool posted but 72 and up. They will bolt right in, but the drive shaft will have to be shortened one inch. I have an 8.5" from a 72 Nova in my 69. The 8.5" was GM's replacement for the 12 Bolt and is almost as strong, and still fairly pretty cheap. If you get lucky and find a 12 bolt in a 68-71 X-Body it will bolt right in with no mods to the driveshaft. Also the 2nd gen F-Body's rearends are a little wider than the first gens.
