First of all!!
![Welcome :welcome:](https://board.marlincrawler.com/Smileys/marlin/welcome.gif)
to Marlin.
Secondly, your not gonna see or get much help for Nissan's here. We are mainly a Toyota site. But if your cool, we might be able to answer some of your questions. But, coming from somebody that had a 85 Nissan for 10 years, Toyota is a much better rig. A 10,000% increase in aftermarket support. I wasted 10 years messing around with mine, before I saw the light. And wished I hadn't wasted all that money in a truck that is nothing but a DD at best.
First off, where is the front output on your t-case? My 85 was dead center. Just below the input. Earlier than 86.5 Hardbody had divorced t-cases. And I can't remember for sure, but I thought the Hardbody style had the driver side output. I'm not 100% on this. So, you will need to find an axle with the diff on the correct side.
Secondly, what kind of stuff do you plan on doing? Hardcore rock crawling? More just trail riding? And how deep are your pockets? The best is if you can go a 4 link and coilovers, but if you DD, you might not like the noise that will come from the links. (No bushings) Springs are a cheaper way to go, but how much fabbing experience do you have?
My best advice would be, look for a Toyota and use the Nissan for parts running.