I just got rid of my 84 J10 a 2 years ago because the parts market was getting scarce. Body parts were getting harder to find, but mechanical parts are found easily. Cab and bed parts are almost impossible to find. You can use some of the wagoneer panels if you get crafty, but I had alot of problems getting stuff. Some of the places where I got fenders, flares, door skins, and rockers, no longer could get them because the demand is so low, so they went out of production. You can still get fenders and a place in Canada makes bed sides, but they are no where near up to spec to just "replace". JW jeep has beds and cabs, but way too high for what they have. Not to be a "Debbie Downer", but make sure the J is in good condition body wise. Look under the floors and behind the seat and especially the cab and bed mounts. They tend to crush easily with just a little rust. Also all the frames on the J series rust out just behind the rear axle back spring hanger. Had 2 do that, but again, I'm in the North. Look it over and go from there...
Here was my1984 J10 back in 1997: