I tow very little and then usually no more than a 5000 lb boat and not far. I was wondering how much pain and money it would be to switch both my axles on truck in sig to a taller gear ratio and what is available for a Dana 60 and Dana 70 ? Would it be worth it for fuel mileage ? I'll probably keep this truck forever even after its not my daily driver.

 

Ive seen this discussed someplace before and the consensus was that the mileage benefit was negligible. Youd have a choice of 3.54 and 3.73 I think. Sounded like the 3.73 was the better all-around choice. From what I found poking around with google, the cheapest ring and pinion sets were about 200-400$. Obviously if youre driving a 4wd truck thats double the expense. Also, setting the mesh pattern is a PITA, either take a day and some special tools (dial gauge, blocks and dana case spreader) or pay someone the labor to install it all.
If youre in there youll want to get a bearing and shim kit and just replace them in one go.
I might be looking at a rear diff rebuild soon, so I might be looking into this myself, especially if its the gears and not the depth/shims/bearings thats bad.
You could also look at a gear splitter, like US gears or something. Not cheap though. About 2k plus driveshaft modification

 

FWIW, I made my own case spreader! Works flawlessly too! and the best part is, Not only did I technically NOT make it (Tool&Die guy @work did) But it was Freeeee!

If I had to guess the cost of the thing, just figuring material alone, no labor. I'd say about $75 and you could theoretically make your own.

You DON'T need the one listed in the FSM. If Anyone wants/needs details PM me, email me (emailmurph@yahoo.com) Or drive on over here and I'll show you the thing!

 

If you have the 4X4, which your sig says, do the rear, do the front. A real pain in the rear. You personal rear.

..PT..