I just went through this with my Jeep. It was stable as stock with a set of chrome soft eights and mild off road tires. I purchased a set of black soft eights and added the Dunlop mud rovers and while balancing the set at the garage the mechanic brought me over to look at the wheels on the balance machine. I found three rims that were not perfectly round. We balanced them out the best we could and the vehicle shook constantly from that point on. Mostly at speeds between 35-45mph. Rotated the tires to different locations and finally decreased the wobble to barely tolerable. I did some checking with others who ran the painted soft eights and many told me that they had run into the wheels not being true. Last week I switched out again to Pro-Comp 8769's and now the Jeep runs smooth and straight with NO wobble. Its like night and day. I will not buy another set of Cragar soft eights. Oddly the chrome set showed none of the problems that i had with the painted set. Oh well, anybody want five "as new" soft eights. If I were you I would find out if your wheels are running straight and true first. If the vehicle worked fine with out the wheels and tires, I think you found the problem. The other added benefit to running aluminum over the soft eights is that the weight difference is huge. Jeep feels like I added torque and horsepower. Good luck,

 

Thanks for all the input guys. I guess ill be doing some additional trouble shooting as soon as it stops raining.
I dont see any unusual tire wear but I still have less than 4k miles on the jeep.
Ill post back any findings or cures that I come up with.