I just finished re-gearing both of my diff's with 4.88's, took the truck on it's maiden voyage this evening. I taught myself how to do gear swaps this summer, cause I was too cheap to pay big $$$ for someone else to do it. It's not really hard, you just gotta have the right tools and be very patient and thorough.
Tools you will need:
* bearing splitter
* press, or a jig that will pull the bearings off
* magnetic base and dial indicator
* torque wrenches - in particular one that measures bearing pre-load, down in single-digit in-lb range.
* die grinder or dremel tool
* some way to heat up the ring gear but carefully monitor the temp
* spanner tool for the side carrier adjusters (I made mine)
* 30 mm impact socket
* Some way to hold the diff safely upside down
* Some way to hold the flange from turning, VERY STONG
* a BIG wrench wrench for the 30mm socket, and probably a cheater pipe (I used the handle from my floor jack)
* Several brass punches of various sizes
When you go to 4.88's, you have to grind the corner off of 1 or 2 teeth of the ring gear in order to get the pin in and out of the carrier for the rear axle. You have to heat up the new ring gear to about 180-190deg to get it onto the carrier, I use an old electric skillet with water in it, and I monitor the temps with my DVM with a thermo probe. I use a Park Tools TW-1 to measure bearing pre-load, I bought it at a local bike shop.
The Yukonn install kits are nice, they actually use Koyo bearings, Toyota OEM shims, and a decent pinion seal. Very complete, although they want you to use RTV to seal the diff in the axle, I prefer using both RTV and a new gasket.
Let me know if you have any questions, I'll try to give you a hand.
