You don't have to line up any gears. The gears are all in the diff carrier/chunk. There is no alignment issue with axles - they just spline into the side gears. Since there is sometimes a minor out of balance in the rear yoke, you mark it to make sure it goes back the same way.

Ditto it's a heavy mutha and will mush you real easy. I like to position a jack under the diff carrier, and ratchet strap the carrier to the jack saddle, then when it's loose, I can just let it down and roll it out to fool with it in the open.

Just so I'm sure we are all on the same page here, you do have an "RD LOCK" switch on the dash, right? Not just the 4h and 4hlc shifter positions?

Buy a new carrier gasket before you start, and some diff juice.