'79-85 toyota front axle. '84 and '85 are the most sought after because they have the most trussing, but any of them will work fine, you can put a truss on them later if you want. grabbing the rear axle might also be a good idea, as they're cheaper than dirt, probably stronger than the luv axle and have a ton of aftermarket support
what kind of tranny are you going to use behind that 4.3? using a toyota t-case might be a good idea(divorce adapters are available) since they're light, very strong and can be geared down to 5:1

you can also double them up
scout ii and fullsize wagoneer axles are also good swap candidates but i think they're a few inches wider than yota axles. they also don't have the nifty drop out third member like a yota axle