I'm not sure of the code. But i do know that all 3rd gens and Taco's use a chain driven T-Case so you will not be able to just swap in the 4.7's. The only way to get further reduction in the T-case is to buy a lefty gear driven case or do duals. all of these are in the 2000+ range
Cant do it. Gotta love that chain drive case. You can also say its probably a no go on the dual cases since its $1700 for the 2.28 taco box from marlin, Plus add x member modifications, And drive shaft lengthening and shortening. And an f150 tank swap behind the axle so you can fit that doubbler in there without dropping the tank..
A 4.7 lefty is pricey to. About 2g's minimum. its basically bolt in.But you will have to modify your add system to get the front diff to engage.
$2500 could get you an atlas 2 spd. but good luck getting that in there under 3 gs
I have also hearrd of some other odd ways of getting different transfer cases in toyotas. Something along the lines of a cherokee ax-15 trans (almost the same as an r150f, both made by aisin) Then using your r150f bell housing and front input shaft and putting that in the ax-15. then you can bold a dana 300 straight to back of that bad boy. I know i read somone did it on Pirate, but it sounds like work!!!!
So yeah its expensive. Too bad you dont have a 5spd (w59) 4banger with a 3rz. Then you can just swap transmissions with an older yota (w56)and skip the first adapter on the doubbler.