[57taskforce]

I don’t think the 12 bolt truck rear was available past 82. They began phasing out in the late 70’s/very early 80’s in favor of the 8.5” 10 bolt and 9.5” 14 bolt SF. Someone likely swapped that one in at some point. My ‘57 is on an ‘88 K5 (yea I know it changed to the R/V series by then) frame and it also had a 12 bolt swapped into it as well from a mid 70’s blazer. It’s been that way since I bought it in ‘05.