Gearbox - swapping input shafts

[rincewind23]

Hi all,
I've got a rover 3.5 litre v8 from a Discovery that I'm planning to use in my roadster. As it came from a Disco, the LT77 gearbox is the 4wd version. I managed to get hold of an R380 from eBay, but it must have come from something else as the input shaft is way too short. I'm trying to swap in the input shaft from the LT77 that came off, but the gears are different sizes. I can't figure out how to get the gears off each of the input shafts to swap them over.

Has anyone done this, or can point me in the direction of any info? I've got the overhaul manuals for each gearbox, but they don't really talk about the input shafts.

Cheers,
KEv.