Going down the highway the other day i notciced my rmps where slightly high for where they should be. My 245/75/16's which are 30.47inches at 70MPH @ an overdrive ratio of 0.75 and a gear ratio of 4.10 should be this

4.10 x 30.47 x 70 x 0.75= 2373 RPM

HOWEVER Mine is more like this:

2639RPM x 30.47 x 0.75 x 70= """(4.56)""" Now if i have 4.56 in the rear, what happens if i still have 4.10 in the front?

It would be very strange to have two different ratios in the same truck. Has a PO screwed it up for you? In this configuration, running in 4 wheel drive would result in the front end trying to pull the truck faster than the rear end is pushing. You would probably hear a lot of wheel chirping on dry pavement or scuffing on gravel. Either that or the weak link will break...your transfer case. It won't last long if stressed like this.

You might have a transmission problem instead. Sounds like it might not be locking up. Could be slippage instead of a gear problem.

Jake

well the PO is my friend i work with and he never changed the R&P. He use to use 4x4 and it worked but then one day the fuse blew and it didnt work, then i fixed all the wiring and now i hear the front dif engage but the driveshaft is broken in the front where it meets. My friend my have the guys number that ge bought the truck off of so ill see if i can contact him. It also seems my G80 doesnt work anymore. i really dont think my tranny is slipping. it shifts thru all the gears fine, and fluid is not burnt.

also forgot too add, My Trans was rebuilt only ayear ago and has a new torque converter as well