I've been fighting an idle issue for a while now and had an IAC off a late 90's early 00's GM 3800 engine. While the plug is 180* from the original IAC used on the CPI 4.3L by rerouting the wiring, the other IAC can be used. The only reason I point this out is because the 3800 valve is half the price of the one used on the 4.3L.
Just trying to pass along some savings since times are tight and there is no reason to spend twice as much for something that for the most part is exactly the same.