Montero has forged crank and cross bolted mains.

Non montero does not. I believe the blocks can be swapped but a oil cooler boss has to be drilled and tapped and a motor mount boss also has to be drilled and tapped. The camshaft in a montero is different than the others too. This is by memory so may not be correct. I think the non mivec 3.8's are all the same other than the montero version. IE cars and endeavor.

I think one of the paj forums or maybe club4g had a great write up explaining the differences and how to build one using the best combination of parts.