truck is stock height. runs smooth, doesn't make it any worse or better if i hit a bump. has dana 44 i assume being as there are upper and lower ball joints. I have recentered the wheels to the best of my ability using conecentric lugs and a strict torque sequence as to pull the wheel in evenly and slowly and i will say this has helped a lot, last thing im going to try is moving front wheels to back and see if that helps a little more. when the front wheels were spun up on the tire skimmer(wheels still on truck) the spindle and knuckle and all did not move, just the rim was hopping around. may even go further to go back to the guy who put my tires on and have him double check the balance just in case.

I have to agree with the u-joint theory. Since you don't notice it in the steering wheel, I assume it's in the back of the truck. They are fairly cheap, and if it hasn't had any in awhile, it may not be a bad idea to replace them anyway. But if it's shaking side to side you may have a bigger issue on hand. Do you wheel it? maybe the driveshaft is bent, or lost a balance weight.

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Sorry, thought I read the whole thread, your truck should have a dana 60 in it. The 60's in those early trucks were ball joints as well. Have you changed the wheels on it? The wheels don't center on the lugs on those, the hole in the center of the wheel has to fit the hub perfectly, I wonder if this could be the problem.

montepig72- I am more encouraged to believe it is my wheels...they are not stock, they are aftermarket 17" pacers and you dont have a way to center them....however, i took each one off then tightened each bolt in sequence a little at a time and it helped tremendously with the shake. I also went to the junkyard and found only ONE set of 8 lug wheels on a 89 d100. gotta double check make sure they are the same pattern, they look the same. Prolly end up taking those and sandblasting them then powder them and they will be able to center good. where could i get teh centering ring?

I'm replacing my engine mounts, one of them is wore right out. If i rev to a certain RPM the truck will shake just like at highway speed.

engine mounts and tranny mounts are new

Fixed the problem fellers, if you get aftermarket rims and can't get hub rings on, dont count on conical lugs to get you centered...get ET Conical lug nuts....they havce a shank on them that will center each wheel hole per stud, only back draw is that you cant just zip them on with an impact got to get at least 4 of them on there slowly and pull it in then get your other ones on....what a difference this has made! Hope this may help someone else!

I put new tires on and that solved my problem.