Transmission issue 91 Park Ave

[volkerc]

just encountered some tranny problems. any suggestions are welcome.
here is what happened. for a few days i noticed that the car getting slower. as if the brakes got applied and then let loose again. kind of a rocking motion. today driving on the highway at 75mph everything seemed fine. until i excited onto another highway sped up for a second and the tranny gave a whiny scream and wouldn't move. i got off the gas and was able to drive slowly back home. not exceeding 35 mph. looks like i'm not getting an upshift. as the rpm is fairly high at 35 mph. is it toast?
It's already a gm rebuilt tranny from the dealer. and total mileage on the car is 180000 miles, but not on the tranny (no idea how much is on the tranny)
any advice?

[maxwedge]

If the fluid is full and you have vacuum to the modulator, I would say it's done, especially if the fluid is burnt.