Rear Tires Suddenly Lock Up Going 65

I think I may have to pull the third member out and take a look. I didn't pull it when I changed the oil, just sucked out all the bad and threw in new oil. But the way the car acted just before the tires locked up makes me think it's the tranny. It was maybe a few seconds of lack of power, then the tires locked up. Maybe some trash in the plumbing wouldn't let a band or clutch actuate/release and siezed all output movement. I don't know everything about the 904 and if this is even possible. But I also agree with the rear end thinking that the tranny couldn't take that kind of abuse and still shift fine/or even function. When I drive it home I will give an update on how she drives and shifts.