Ive got a 99 tracker with a 4.3 700r4  and a solid axle (samurai ) & a samurai stock transfercase. I put this together for a winter daily driver /light wheeling (plus I like playing with samurai,s & trackers . it has the 4;88 gears in the axles stock axle rear & samurai steel ft pig . I have a rig with real similar drive train only it has 3:73 sami gears  in the axles & it gets 25 mpg the tracker is getting 7mpg and its running high rpms
 what Im thinking of doing is  fitting a samurai rear third into the tracker rear by attaching a mounting ring in the hole for the stock pig I think that should work since  samurai rear spool & tracker spool are the same part #  so that I can get 3:73 gears & better mileage
any thoughts ?

They make a 4.30 for the tracker.

I knew that but I dont want to spend the money on 4:30s when I have a bunch of samurai 3rd members and some bent housings to get what ever i need to mount it to the tracker axle  I just dont want to re-do the rear suspension plus Ive got more time than money
Ive compaired a tracker rear third  to a sami third with a tape measure & eyeball and it seems like it will work. I was going to build a custom housing w/ the sami center & tracker tubes when I hatched this idea.. Ive never wanted to go from 4;88 to 3:73  its always been the other way  but Id like to be able to(afford to) drive this  because it has a cool look I want to get all major mechanical  done before it gets painted

Ya I'm taking the 4:10 Toyota axles out of my red samurai for the same reason the extra weight and gas mileage,I think that the 4:10's would of been a good ratio for my 6.4 to 1 Transfer case with 33's but i'm going back to a 31" tire with stock axles.