Did you manage to find anything yet? Several years ago, I read some budget build articles in Super Chevy or Hot Rodding on building up the 8.5. I found an 8.5 inch 10 bolt in an early 70's Nova at a junk yard. According to articles I read, the 8.5 has much of the same guts as the 12 bolts with the exception of a slightly smaller ring gear. I stripped it down to the bare housing and bought that for $50. I put about $1500 into it to have it built up with a nice posi and forged axles.