I seem to have mis-judged the interchangeability of the different Kelsey-Hayes calipers. Calipers on my wife's 1986 Jetta GL 1.8 8v were rusted up pretty good. I was given a '90 Jetta GL a few days after purchasing it. Tried swapping the newer version caliper onto the '86 only to find out that the slide bolts are about 1/2'' longer.

Has anyone else tried a swap like this? Am I out of luck?

Any and all input will be appreciated.