Motorized Wheel Chair Source

You can wait on doing the SYE and CV. Most people are fine without them, but the SYE is stronger, so you may plan on doing that eventually.

If you have 4.10s now, I'm assuming you have a 4-cylinder, 5speed. If you want to keep your power and gas mileage, with 33s, 4.88s would be best, but many get by on the 4.10s for a while. If you go 31s, 4.56s would be better than your 4.10s, but I wouldn't bother regearing for 4.10s.

As for a locker, the rear axle won't live long with a locker. This is part of a response I did for another question here, it will help you as well.

"Spools are beginning to become more common on street driving rigs, however your Dana35 has no hope of living with a spool in it. It you lock it it might live for a while, but it will break.

There are a lot bigger advantages to locking the front. First and fore most the front axle is actually strong enough to handle the locker. A rig with just a front locker will perform better than a rig with just a rear locker.

Its not if a Dana35 will break, its when. I’ve personally witnessed 3 let loose on the street, and 3 on the trail, me included. I was one of those people who thought I was easy on the gas peddle and I wouldn’t break a locked 35, mine went letting the clutch out, and I was letting it out easy. On the web it seems half and half, half break them, half of them are still pushing their luck. Either way those aren’t good odds.

As for the front locker and bad weather, I was a little concerned in my rig (locked front and rear), but now after all the snow we got, I love my front locker, where ever you point the wheel and gas it, it goes.

Get an Aussie locker for the front, you won't be sorry. "

As for the carriers, with 4.10s already you won't need a new carrier for anything 3.92 and up in the front, and 3.55 up in the rear.

As for what you have now in your axle, there is BOM (Bill of Material) stamp on all Dana axles, you can decode them at Dana's website, and it will tell you everything you would want to know.