Changing the the ratio of rears

You could probably swap them out for a rebuilt set rather than rebuild those.If truck has a lot of miles , may be due for rears.Around 5 thousand bucks, depending on rear type. Possible you have full locking set ( used in off-road / heavy haul applications ) , VERY expensive to rebuild. Try it first. 18 could be a double over.

 

I totally agree! I just built one for my trucks and the o/h kit was $550 compared to others at $250. Expensive but bulletproof!

 

With the specs of the truck you gave I would bet the tranny is a rtlo18918B. If it were a 18918A it would run a little lower on the rpm but no one puts a "a" in a heavy spec truck.

I just changed out my rear pumpkin to add a locker and it was 3500 so you could double that and it may be a fair bet. I highly doubt a truck specd like that will have low profile rubber so changing the rubber would be worse idea.

You could put a ad in a online heavy truck classified offering to pay the swap if someone wants to swap rears with you, it's a long shot.

 

I'd swap if the specs were right!

 

Does anyone have mpg numbers after a swap?