I realize this is an old thread but...
I brought in an Isuzu 4x4 camper from Japan and the 5 speed manual transmission went out. It's the same MUA/RMN transmission used in the US except the bellhouse part which is integral to the case is different. If you have the skills to rebuild a transmission or if you want to try and swap a domestic 2.6 or 3.1 with a transmission into it you could have a great rig. I have over 12k into it. Will sell for 4k The 4jb1 diesel in it now smokes on start but pulls strong. The core on the engine is worth over 1k on ebay. Someone with skills could have a 4x4 camper with an fiberglass shell for 5k when all done. You could sell it for over 10k easy.
For a price comparison google jdm sales in seattle, he imports and sells them.
this is the actual rig. I've made some improvements (all new RS5000s and timing belt, brakes, etc)
https://www.youtube.com/watch?v=jK7F_jnSpIgI'm in lake oswego/portland - Bill 503-708-0224