Rear crankshaft seal replacement 2001 Montero XLS
 

Can anyone give some insight in replacing rear main seal?

You have to pull the engine to go that. No other way to get to it. I think you can get to it by removing transmission. However, removing and installing rear main seal carrier is difficult without removing the oil pan.

I was thinking of removing the transmission, I have the manual exploded view and process order but havent been able to find any videos or anything showing it being done.

Whichever way you're going to go about, it's a lot of work. You're going to work with heavy hunks of metal. Do not hurry and make sure you're doing it safely. Best of luck.