may want to do some research on what axles, transmission, transfer case, and engine it has. once you know what its got, then we can tell you which ones to scrap, and which to keep.
im almost certain that the front axle will be a low pinion passenger side drop dana 30, no bad for moderate wheeling with 33" tires. the rear axle could either be a chrysler model 20, which is just better off left in a scrap pile, or a Dana 44 which is a great platform to build on. although i do know plenty of people that have done well with the model 20 rear-end. the transfer case should be a dana 300, which is a gear driven t/case, pretty small but pretty tough too. i dont think the low range ratio is all that great though. transmission i have no idea, auto or manual. i know they used a few different tranny's in those older years. and the engine if you say is a inline 6 the nit would be the 258. again, a pretty good engine. may need a better carb set-up though.
i think the drivetrain on these jeeps was pretty good, the problem was the frames likes to rust, and the bodies. so if you find one with a good solid frame and body, then you lucked out big time. build off the good parts, and toss the un-good parts out in favor of better options. this is the jeep world, we swap anything and everything into our jeeps to make them better:) good luck! send pics!