I've searched but seen no mention of using 15X10 rims with 6.5" backspacing on the rears of 3rd gens. Anybody know if they'll work?

 

Probably not. It would push the wheel too far inside the fenders. They would probably work if you were using a 4th gen diff under a third gen.

 

If your willing to bang the hell out of the fender whell's it can work. Glad to see someone trying to go with the proper backspacing with wide wheels for once.

 

100% - 6.5 would put them under the car(where they should be) but would probably put the tires against the inner fender well. Not drastic, but would deffinetly need some hammering/cutting around the bumpstops.
- and for the record, I'm running 8" b/s with 11 wide wheels on my 4th gen rear. Sits square with the body lip, so 6.5 b/s and 10" wide would stick out.