you need the front pots from the tracker, 462 auto, 512 standard. Not all LWB have the 390, I've got one and it's got 373.
You can bolt in the front tracker right into the front of the samurai but the tracker pot is alot weaker. some people have bolted the front pots into the rear with a change of the side gears but every time my friends did it they blew them up real fast.
I'm running 512's with 30's...this is real slow but wheels great. My friends all run 33's with the 512's and run good.