Speaking of J-10. I had a J-20...the 3/4 ton monster "Brutus" with solid everything considered suspension. It rode like the kidney transplant team was just waiting to hear you were in town... 401 high capacity V8---and I mean 12mpg IF I was lucky. Lotsa power, handled pretty good. Rode like a hay wagon on cobblestone.
I got it with 47k on it about 1982-nearly new.... planned on keeping it a long time as I liked a lot of its features.
It started having little snits where I could drive for a couple hours (or minutes) and it would just quit. Sit for 1/2 hour or so, it would fire up for maybe another 100 miles, 24 hours, or who knows.
Had all possible checks, tunes, trouble shooting, engine/brain box/etc closely scrutinized by specialists in 3 states. Went on a 2000 mile road trip that cost $800 in towing...and never left the pavement.
Had the ultimate hot rod shop check it out, AND the ultimate Jeep dealership in Portland, Boise, Pocatello, Missoula. Couldn't find the trouble. It got so it would just die for 2-3 days, then revive & go on.
I finally made it back home, it actually ran 400 miles without incident. I had spent $thousand$ trying to make it work.
The day after I got home, went out to drive down town.
It was dead again.
I had it towed away and bought a GMC 4x4.
Strange, that was about 23 years ago, and I've never had to use my towing insurance since.