Cusser
+1y
Can you post some good photos of what your set-up looks like? And tell us ifyour 1987 is a B2000 or a B2200.
I know the B2200 (likely the B2000 also) uses three belts, a separate one for the AC compressor. There's no idler pulley for the AC belt, the compressor just rotates farther away to tighten the belt and is locked in there to keep it tighten. There should be three grooves on your crankshaft pulley, if yours is the correct pulley, like one groove for the AC belt.
Are you sure that yours ahs the correct compressor? There should be a Sanden number, like SD 708 followed by a dash and four more numbers, post those if you can read them.