My T-6 has 83,000 miles on it and is starting to vibrate in 3rd and 4th gear when accelerating. I don't think its the tires because when I let off the accelerator the vibrations stop at the the same speeds. A new transmission was put in at 72,000 miles and my service person assured me that software downloads were done but I never know with those guys. I think its in the drivetrain and not the suspension. I took it to and indepentent shop for rotors and they looked it over briefly and then I took it to a dealer for torque arm bushing and ask then to check the transmission, niether found any thing obviously bad. I plan on going back to both and have them ride with me. I'm hoping its as simple as a software fix but I'm expecting the worst. Any suggestions or ideas?

We havent seen problems with reman (replacement) tranny's but anything's possible. I'd suspect that either it needs the latest trans software (which any dealer can check with their Vadis PC by checking your current software PN in the cars trans ECU) OR your replacement trans might need an STH solenoid, but not as likely.

One word: Kazaa.