Dustin_89sportstruck

So I've really been tossing around the idea of doing a 4bt swap in my jeep. I've seen people on the internet do it to all sorts of vehicles from nissan 240s all the way to full size pickups. I just want some inside knowledge on what all I'd need to do before I take on this project. I love my 4.0l but it's getting tired and i think something like a 4bt would be a good replacement.

I have an 1989 Jeep Comanche SporTruck and I went and had new tires put on it yesterday and the tech and Les Schawbs told me i needed to replace my rear axle bearings. I went to the local parts store and asked for the bearings but to my surprise there is more than one rear end. How can I tell which rear end is it? It's all factory original