On a cold morning, I will shift into reverse backing out of driveway and it sounds like the tranny is humming. Doesnt do it in any other gears, and it only does it when its cold. Also WOT it slips around first, and second. Please dont mention the word rebuild.

 

mine does these exact same things......but my tranny was rebuilt 20k miles ago..... im interested in hearing the answer

 

from what ive heard the whinning noise is normal when cold. the slipping could be that it just needs the bands adjusted. im dont know the proceedure for that but it should be in the haynes manual. there might be some info on it here too if you look.

 

How is the fluid level?
Is the TV (throttle valve) cable adjusted properly?

You can tell its getting cold around the country as this question is popping up a lot. From what I have seen its normal. I am not sure what is causing it though.

Since I am curious, under similar circumstances that you are hearing the humming put the tranny in manual low (1) and listen for the hum.

 

The pressure sensor (transducer) is also know to become 'saturated' at WOT, and fails to read correctly as well. Known issue for these trannys.

 

as said, whining/groaning from the pump in reverse is pretty common. mine does it too.

for transmission - read throught MonteC's thread. he frequently recommends replacing gov pressure sensor and solenoid, including replacing it with a GM conversion kit. that's an easy job done just by dropping the pan and nothing else. after that, there is a sure-cure kit that can be installed with more effort. after that... its the unspeakable (you might back off the WOT to avoid WOW (wide open wallet)).