I have a high speed vibration that starts around 90 mph and gets worse the faster I go. So I haven't been driving that fast anymore because I don't want to damage anything. I have had two JPC driveshafts, three spyder shafts and I currently have a shaftmasters on there now. The vibration wasn't there with the factory shaft. I recently install a detriot truetrac with a new FRPP 4.10 gearset. I install all new bearings except for the axle bearings. The gears are quiet and the pattern was great, the preload was spot on. I thought it was the driveshaft originally because I got most of the vibration out of it with hose clamps on the JPC shaft. Since I sent the other JPC shaft back I got a sydershaft. I waited to install the shaft because I was going to do it all at once when I did the reared build. I have checked the pinion angle I have tried -2 and -1. The pinion angle didn't change the vibration at all. The first driveshaft from spyder was really bad at 60. The second shaft was better and the third shaft was great to 90. This lead me to think that the problem was with the driveshaft, after installing the shaftmasters driveshaft the vibration had seemed to be less but it is still there. I have checked the balance and road force variation and rotated the tires. Still no change, I inspected the axleshaft when I did the install of the rearend. But I never checked them with a straight edge. I am really at wits end here. I will be installing new axle bearing soon and checking the integrity of the axle shafts. Any suggests?