'70 Suburban fuel milege

[jku72]

If you have the "granny tranny" with the very low first gear, use it, and swap to a 3.07 rear. The ultra low first gear is like 7:1 ratio, more than is needed on anything smaller than a 2 ton truck. I have a 350 4 speed, and swapped in a 3.07, and went from 14 to 19.9 mpg. All this is based on an important assumption, that is that you have the versatile 12 bolt rear, for which 3.07 gears are cheap and plentiful. I did my whole swap for the high price of $75 dollars. I got excellent used gears and a carrier from a bone yard, and they gave me money for my 3.73 with carrier. Most hot rod guys want the 3.73, or 4.10's, so you could trade even or end up making a profit on the deal if you do it right. Now, even with the 3.07, I can tow heavy loads(like a car on a trailer) and still get decent mileage.