[HOTFUN]

Jon , On my '66 327 with ps truck and with the 1966 dealer installed factory air kit it had that 3791943 stamped pulley on the ps pump and uses the cast iron 2 belt crank pulley. I had a nos correct style 66 power steering pump so I found and used a nos 3791943 pulley on the nos pump and the alignment is dead on everywhere. I also believe at least in 66 to 67ish on the factory installed 327 ac trucks they used the 2nd style 3 belt heavy cast iron water pump pulley with a fan clutch. The GM accessory factory air kit appears to have provided an added single 2nd belt pulley and spacer in front of the water pump single pulley for the ac belt and of course a 5 blade fan. The fan clutch appears to have been another option from the GM parts and ordering books. With my years of experience changing out leaking WP's from bearing failures, I believe GM shortly realized this and quit using that unbelievably heavy mass hanging on that bearing due to failures and went back to using stamped steel pullies. So on mine I utilized the factory air GM kit steel pulley set up and and added a new fan clutch and cross my fingers that this holds up on a restored painted engine. My truck frame comes back from the exhaust shop this week so it's time to post some engine/chassis pictures to show what I came up with. Mark