Just wondering, whats the rear end ratio on your 4.3 S10? I have a 96 C1500, with the 4.3 and a 4L60E with 3.73 gearing, and it gets 20-21 highway, and about 19 city. From what I'm starting to see, they seem to perform best with the 3.73 rear end.
IMO, if you want a powerstroke, go with a...