I just bought a '72 Chevelle and want to upgrade the rearend to a 12-bolt since I'll have a 522 under the hood. I have located a '71 model Concours wagon with a 12-bolt rear end. Is Concours just a trim package of the basic Chevelle and if so, is this rear end a direct bolt-in? Hope so as it's so cheap I can't pass it up. Thanks in advance for all your help.

Yes to both of your questions.

Check the rubber jounce bumpers. The ElCamino (and I suspect the wagon, too) has its jounce bumpers on a bracket that raises them a little bit compared to the sedan. The bracket and bumper unbolt and can be easily replaced with the sedan part. Other than that the rear ends are the same.