tranny mounts? wheel bearing? i'm kinda shooting in the dark. if your rear springs are soft it is possible that you could have torqued a u-joint again. last time i did mine it was a dry joint which was frozen so it wasn't real clear that was the problem till i pulled it. because it was frozen solid it was effectually shaking the tranny on every revolution. probably not the front joints as your disconect will leave that stationary. tires out of balance could vibrate you too, or runout in your rims. you should put your jeeps stats in your signature line. had to dig around to see that you drive an 87 wrangler. i'm assuming stock? good luck with it.