Old thread, but I figured I'd post my findings after doing the v6 caliper swap on my '85 ST.... As yello620 stated above, the v6 rotors are 4mm thicker. So what happens is that you lose 4mm of clearance on the back side of the rotor where the caliper bolts to the spindle. To compensate for this you need to have the caliper brackets machined down 4mm for them to bolt on correctly. Also, since there is a change in diameter, you lose wheel clearance so you may have to up-size your wheels. But the good news is that the mounting spots are in the same position so they do (with a little help from a friend at machine shop) bolt on directly.