Old Blue,
My truck shook like a paint shaker until I put new radials on. Since you already them on back, I would put them on front. If your truck was ever stored, the tires will go out of round. I have seen it on 04 and 05 cars that have been on the lot but not driven for a few months. They shake like crazy.
Also check your king pins and bearings. But start with the tires/rims. If you are running stock style rims, make sure they are straight. I had one rim that was all bent up. My problem was up front. Worn or out of adjustment front end parts made the bad tires even worse.
