I am running a 401 that was originally in a 1975 J20. I have transplanted the 401 into my 1991. Seven years ago when I did the swap I didn't plan on ever using the York ac compressor so for some stupid reason I ditched the 3 groove water pump pully for a 2 groove.
Now I am reinstalling the York for on board air and of course can't find the 3 groove pully. I was able to find one on the internet. What I have found out is the 3 groove pully I have purchased is a bigger diameter and none of the accessories line up at all. Is there different pullies for different years. I have to admit that the a/c set up on my truck is different then any pictures of amc's with air I have seen. My compressor only has a single belt, one idler pully and one tensioner pully. Most I have seen have 2 belts on the York. Anybody have any ideas where I am going to find the correct pully. Also the 3rd groove on my harmonic balancer pully, which is for the a/c compressor is larger then the power steering pump and Alternator pully.