Seem to remember reading that the drum brake 3rd Gen's used the same odd style axle flange as 8.5 10 bolts. If so, while this does require some cutting work on the axle flange, wouldn't it be a viable option?
http://www.thirdgen.org/newdesign/tech/ls1reardisc.shtml
http://www.thirdgen.org/newdesign/tech/ls1reardisc.shtml
