87-89 KM-145 differences?

[FMS88]

this should mean that i can swap yokes to use this trans/transfer case

I think that's a sound conclusion. But check the bore in the yokes. If they match (.985" or so), that will confirm that swapping slip yokes is a possible option.

Also, measure the dimensions of the two slip yokes. If the outer length of the slip yokes and the internal depth available for the transfer case output shaft are similar, you should be good.