I'm in the middle of my gas--->diesel swap. I tried to swap the double pulley on the water pump from the gas engine to the diesel, but it's interfering with the crank pulley. In other words, it's diamater is too large. I wish I knew this sooner, so apparently there's a differnent pulley for ac models, unless I have this all wrong, and the single pulley is supposed to run the water pump, ac compressor (which in turn drives the alt), and the PS uses it's own single belt using the outside track on the crank pulley?