Kennedy,

Are you sure it is the diff. When you said shakes badly at speed, do you see the pick up bed, bouncing and or "twisting" a whole bunch? It most likely needs the vibration damper installed, and that really is no big deal. When I am on relatively smooth pavement my rides fine. When I get on certain types of pavement, like the Hardy toll road at ANY speed the pickup bed goes completely crazy and shakes the entire truck violently. The bed actually twist up and down from side to side, sometimes I think it is going to fly off the truck.

Vibration dampers ARE NOT a big deal. Zillions of good high quaility cars have them. My Avalon, I had 4 to 6 of them on the bottom of the car. In that case most were attached to the exhaust system, and averaged maybe 5 to 7 lbs each. There were also several in the engine compartment.

Also, if I drive over broken concrete in city streets at slow speed just 15 to 25 mph, it will do the same thing. You can see it do all this in rearview mirrors, all three of them.

Mine is about 3.5 weeks old and about 1,500 miles. The only real problem to date is that have not been able to fix the AC, which did not work from day one!