I have a 46 Ford with a Chevy V8 and TH350, was driving last week when intermittently the RPM's increased but was not getting power to the wheels. It got progressively worse and finally had to pull over. After about 10 min I started up and it seemed fine for about a mile the again lost power to the wheels, engine was running fine. I shifted to second and first but was like the transmission was in neutral. I checked the fluid and it was over full. Was able to limp the car home a mile at a time, letting it sit for 5 to 10 min before it would move. The transmission shifted fine each time until it started slipping. I drew out excess fluid, took it for a spin and that did not help.