Driving down the road the transmission shifts good until the speedodometer goes to 35mph and speedodometer goes crazy and the transmission starts to slip?

It sounds like there may be an issue with either the vehicle's speed sensor or the transmission itself. When the speedometer goes erratic at 35 mph, it could indicate a malfunctioning speed sensor, which can confuse the transmission control module and lead to slipping. It's advisable to have a mechanic diagnose the problem, as it could involve electrical issues or require a Transmission Fluid check. Addressing these issues promptly can prevent further damage to the transmission.