i have to replace the oil sending unit and was wondering if there was a special tool i have to use to get it off?

 

I think I just used a wrench on mine. It'll thread out of the stand-pipe // 90* fitting. There is a bunch of stuff in the way on the SCFI motors (96+) and I know that the CPI motors have the plenum pretty damn near covering it... You may have to find a really deep socket the appropriate size to get onto it if you have room from the side.

One thing that I've done before as well is buy a cheap deep socket, chop it in half and add in a length of pipe to make it even longer inorder to fit over some sending units (Dad's '94 K2500).