[adkl1]

hi im a new 08 pro-4x owner.. love the truck but i have a few problems to get worked out. I flew up to SAN FRAN to pick this truck up and drove it home to the PHX area had a great time driving down the coast but when i got to the LA area i noticed i had a side to side vib it starts around 65mph and stops around 76mph. i dont feel it in the steering wheel but it shakes the seats so i stopped at a tire shop and had the front two tires Road Forced Balanced (watched the tech) they got them back to spec. I continued home as i was going over a bridge bam(DEATH WOBBLE) i knew what was going on so i slowed down 55 and got it under control then it happened 3 more times.. The concrete freeway turned into asphalt so i set the speed at 71mph and was getting that shaking all the way until i got to AZ and was able to bump the speed up to 81mph BAM no more shaking.. has anybody had this same problem? Any info i can give the dealer would help out so they can fix this problem.Could the drive shaft not be balanced right ?? please help this will drive me crazy...