from what i have read, it seems the 4.7s had some qc issues. If you find a good one theyre great, and the bad ones, well you get the picture. I have a 3.9l auto in my 97 2wd reg cab short box, its definetly not fast but it runs awesome and i get 19-21 mpg with it. All I did was build a cold air intake for it, pulled the rubber flap off from behind the head light to allow more fresh air in, 2.25" exhaust with no cat and a flowmaster. Its loud and doesnt sound very good above 3k lol but the combo gets me pretty damn good mileage! haha good luck on your search!