so my water pump blew on my 4.9. thought it would be an easy fix but i thought wrong. I work at napa so I picked up a water pump at work and went home thinking id have it back together in an hour or two. but when i got the old one off and held the new one up to it there were some differences. the flange for the mount bolts was much thicker than the old one. i wasnt to worried so I went out and found some longer bolts and mounted it up. but when I went to put the fan and clutch back on, the threaded shank on the pulley flange of the new water pump was too big in diameter and did not stick out far enough. So I took it back the next day and checked every other water pump napa can get for my truck and they were all the same. same story at carquest, checker, rock auto. I tried ford, but when they gave me a 300 dollar price, it didnt matter whether or not it fit. just wondering if anyone else has encountered this problem. Im thinking i may end up having to use the napa pump and junk the fan and clutch and put in an electric one. thanks for any help