Still have driveline vibration problems
I have been fighting a driveline vibration ever since I installed a new pumpkin that I bought off Ebay with 3.73 trac loc in it. It is a cast itron pumpkin. I had new u-joints put on the OEM driveshaft and then had it straightened and balance. THat mad eit worse. THen I had the same shop make a new one piece steel shaft with the original ends and it was better, but still gave vibration at highway speeds, finally I broke down and bought a 1 piece aluminum Mark VIII shaft and put the new u-joints on it from the other shaft and I still have a vibration at highway speeds. It is definately better, but still gets real bad at 80+. I am scared to take the car to the dragstrip because I don't want to know what might happen at 100+ mph. I am speculating that because I put new u-joints on the aluminum shaft, that I may just need to get it balanced, but I do not want to go to the same place that already did my stock one becasue they didn't seem to help. So does anyone know of a good place between Atlanta, GA and Charlotte, NC to take a shaft to be balanced. THe other question is, is there a possibilty that it is somehitng like a halfshaft issue, or an imbalance related to my rear drum brakes. I have not rotated the tires yet to eliminate that, but it just gets constantly worse at highway speeds. Could be something about the pinion angle of the pumpkin, or something internal to the gears? Any recommendations would be greatly apprecaited.