I know this not a Nissan truck but this might give you some ideas. I swapped in a 1991 Chevy 350 small block into my 82 Dodge D50 4x4. What an amazing increase in power and torque. Trouble is I started breaking axles so I had to swap them out for a Dana 44 up front and a Chevy 12 bolt in the rear. Here are some pics [Linked Image] [Linked Image] [Linked Image]