Gearbox Swap

It will fit in the back. Tie it down and drive it to a workshop.

You will need a complete gearbox and transfer case compatible with your motor and driveline (constant or part time) The front flange of the rear tailshaft will also be different bolt pattern, so a complete tailshaft or just the front slip yoke and a balance afterwards....whilst you have not gave any indication on motor, i would think you have a 1hz with r box. If it is a gxl and you have full time, you need a tranfer from a 100 turbo diesel or a 105 petrol constant. The actual transfer casing holds the 4wd lever, unlike the 80 series that is on the box. If you have a standard van and part time, a simple 80 series gearbox and transfer works, as the lever comes out the floor under the dash. The r151 rear tailshaft has hilux /prado/ sized uni on the front of it. The h150 transfer has larger cruiser sized flange. Tailshaft length is also different full time to part time. Lastly.....if you buy a petrol 1fz gearbox or a turbo diesel hdj80 one, the front spline on both are thesame, and different to 1hz, but an izuzu 11 inch clutch plate marries them together. So there are many options to get you bulletproof.

Wow....You really know your stuff. Thanks.
Engine is a HDT out of a 80 series with the gearbox.
So will the 100 series box fit straight in?

Cheers

ok, ive been there done that, not a mechanic, but have owned many cruisers over the years. The transfer case from a v8 100 series manual or auto will fit to your hdt 5 speed, a factory t/d 100 transfer or a 1fzfe transfer from a 105 will all fit, as these all run the same gearbox you have bought with the motor. IF you have a GXL 1hz with r151 and transfer, the splines are different on the 2 shafts, h151 to r151 transfer, so you need to source one of the transfers i mentioned earlier, if you have a std van, an 80 series transfer will work and 4wd lever comes up through the hole in the floor. All that aside, if you are asking if the current r box you have will bolt up, and its a 1hz your changing, the clutch splines are different, and the clutch sizes are different. The r box will not last, nor will the 1hz clutch, but if you want to give it a go, you need to swap flywheel/clutch from 1hz to hdt.