Mine is not lifted at all, not even a leveling kit. the 275/75 17 toyo's fit perfect, and actually look "normal" on the 2500's. The 265/70 stock size just flat out look funny they are so small on that truck.

 

4.56 gears are now in. BIG difference, truck actually runs like I would expect a big 3/4 ton truck should. I only have probably about 20-30 miles on them, but driving /performance wise, much better in all catagories.
So far looks like a improvment in milage for 90% of the driving I do (90 km/h range mostly) according to the onboard milage computer which has been recalabrated for the tires and gears via superchips. The 4.56 and 34" toyo MT combo seems to be perfect for this range. I expect a milage hit above 100 km/h, but better perfomance (hills, passing, etc.) there as well, but that might be 10% of my driving. the 90% is hilly back roads, and old, bad dirt roads.

Quite happy with the change

 

at that speed (90) and those big tires, it must have a been a dog in those hills for sure. Glad to see it's working out for you... now hopefully you aren't going to wish you had gone 4.88 in a few months! lol

 

I'm almost positive you can't get 4.88 in the 2500's with the 9.25 front and 10.5 rear....either way, that might be a bit much. the 4.88's would REALLY have the rev's up even at 90 km/h, and the odd trip down the freeway / 4 lane would be pretty bad I think. I think MOST ppl (not me)might actually prefer 4.10 with the 275/75 - 17 toyo's, as that would put it pretty much right back to stock overall gearing.

 

I forgot you had 3.73 to begin with. 4.56 is probbaly a good enough jump in revs as it is even with 34" tires to bring you more in line with the stock 4.10 trucks. Especially if you're not towing/hauling much.

 

Yep 4.88s are only for the 2wd 1500s. Just make sure you break in those gears properly OP!

 

I've gone through a few gear changes already, but always in modified jeeps....lol
I think some go a bit overboard breaking in rear end gears. after spinning everything around by hand, crawl around (idle) listening for any funky noises, or sensations (vibes, clunky feeling, whatever). Then a nice slow progression up to 20 mph or so for a few min, then up to 30-40ish for another 5 to 10 min, then let it sit for a hour. After that I simply drive "normal" for me, try to stay off the fast interstate/freeway's what have you for the first 100 miles or so, as well as stay away from 4-low hill climbs, and after that I call it good to go. I actually go out on a old bad (slow) trails and crawl around in 4x4 a bit to get some controlled power going through the front end.
Never let me down yet, and I have put some serious punishment on my purpose built off roads jeeps when I had them.

I have only ever destroyed one ring and pinion set, and I know exactly why I broke them, and it was not due to improper break in...lol.
Trying to get out of a river here in winter over a frozen ice shelf, and kept sliding back after getting part way up into the river which had a solid rock bottom. Didn't get off the gas soon enough one of those times and landed on the rock under power with a dana 44 with a locker, 4.88's, and 37" bias swampers at 5 psi (snow wheeling) and the tranfer case with 4.1 in 4-low. The rear end didn't stand a chance
Gone through a lot of axles though...lol