transmission question

Please help!!! I don't have much money just like alot of you out there I'm sure, so here goes. My 96 tahoe starts fine, tuned up regularly and has 160,000 miles. my transmission makes a whinding noise when its at operating temps and start to slip in drive. I lose reverse gear also and it seems to run fine until the fluids get hot. is this a torque conv. issue or should I just change the tranny fluid? thanks in advance for your help!

It could be a worn fwd/reverse abuse bore plug in the valve body. The valve body would have to be removed to inspect it.

//2000CAYukon

Welcome to AF. Also reverse clutch hub spline is very common here, unit will have to come out and apart for this, a pressure test in reverse will confirm 200CAYukon's suggestion.

It only slips and loses reverse when at temperature? Does that mean reverse operates when it is cold?