i have a whine in the drive train from 20-80 mph then 80+it seems to get quieter. is it rearend, trany,U joint, or what? it seems to shift fine and the rearend is full of oil. it started about 800 miles ago and is getting worse. when i jack it up, it only does it in 3rd and 4th gear but when i drive it does it in all forward gears even in neutral. Its got me stumped and i only want to take apart what is wrong. Any ideas?

 

Well if it makes the noise in neutral I wouldn't think it could be the rear end or u-joints because they shouldn't spin in neutral. So I would guess something in the tranny.

 

Yer planetary gears are probably coming apart. Hows the fluid look/smell? Drop yer trans pan and I bet you got metal shavings (silver).
It could also be your torque converter going bad, or the filter plugging up from something else coming apart (clutches).

Drop the pan.

 

so your saying it is probly not the rear end and is in the tranny. the weird part is is that it gets quieter at 80+ I'M thinking about a tranny flush and change oil in the rear end and hope that solves it.

 

My experience with this type of noise ended up being my tranny pump.