I have a near new R154 gearbox here that I may sell. It is basicaly brand new, but was rejected due to a very very minor noise but otherwise works perfect. (I work at a dealership). The only problem is that its to fit a Prado or Turbo Diesel 4x4 Hilux, so the bellhousing and shifter housing is to suit that. Anyone interested?
AFAIK R154 never came out in 4WD. They either had R150 or R151, difference being gear ratios, shorter input shaft and extension housing i.e. R154 to join to tailshaft, R150 - R151 to bolt to transfer case. Id check more carefully what box you had there.
R154 came in the 3 litre turbo MKIII supra, 2.5 litre twin turbo MKIII supra and 2.5 litre twin turbo soarer. May have came out in a few more random 1JZ powered toyotas, but would be really rare.