I've had a squealing sound coming from my Transmission for a couple of years now. It's never caused a mechanical problem, but now that it's summer out and I have the doors off, it is all I can hear. The sound happens when I accelerate. The pitch changes depending on how hard I am accelerating, but it only happens when I am accelerating (as opposed to just revving it at a stop). Here's what I have had done since the sound first popped up:

• Throwout bearing replaced with the correct preload done on it per the TSB (Didn't fix the squealing but did get rid of the occasional rattling sound)
• Clutch itself was has been replaced
• Both driveshafts have been replaced
• Front U-Joints on the axles have been replaced
• Front upper ball bearings replaced
• Gears have been replaced

I think that's about all the driveline work I have had done and none of those things affected the pitch or frequency of the sound. The sound does not change pitch when I lightly press on the clutch. I know the squealing sound has been discussed nearly to death on these boards, but none of my searches quite found another problem exactly like mine. Ideas or suggestions are welcome.