Bobby,
I installed the RV-7 crotch strap kit on my flying -6. The parts for the 7 didn't fit the 6 exactly, but with a little "make it to fit" they do now. Sort of the way the whole airplane is built. I don't have any pics, but they way Gary did it (previous post) is pretty much exactly like I did.
IMHO the crotch strap should not be an option, it should be a standard part of every kit, and all seat belts should be 5 point. Even if you never fly aerobatics, the 5 point harness is much more effective in a crash, as the crotch strap holds the lap and shoulder belts in the proper place. Plus, the whole arrangement is much more comfortable for everyday flying, as the crotch strap keeps the lap belts from riding up on your hips.