is 10 mpg normal?

[tekno62]

Need some help- Im confused. I just jacked up the truck - I kept one tire from not moving I get 1 and 1/3 tire spin to one drive line spin. the truck is to have posi from what the spid shows but when I turned the tire the other side would spin in the other direction.

Originally Posted by Woody

The quickest way to check your gear ratio is to jack up both rear tires, then turn the drive shaft and count the turns it takes to rotate the tires one full turn. make sure both tires are turning. So then 3 - 3/4 turns of hte drive shaft for 1 rotations of the the tires is a 3.73 gear. a little over 4 is probably a 4.11, a little over 3 is probably 3.08.

You also can look at the glove box sticker, it may have it listed if it is still there and the rearend hasn't been swapped out.

Oh! I have a 350 / 400t w/ 3.73 gear and it only got 12mpg. I installed a 305 (from a 86 chevy) with HEI and the best I could ever get was 13-13.5 on the highway running 65-70. Like everyone else it really does not matter if it was loaded or not....