95 Deville 4T60E Trans
 

while on a 128 mile trip, my 95 Deville would slip out of gear while driving at 65mph. After I turned off and restarted high gear was back and could get back to driving. This happened 6-12 times in the 128 miles.
When I woke to go to work the next day, I put it into drive and the car shuddered a bit then started slipping drastically. Now it won't move at all.
No rattling noises at all, the fluid could use a change but I fear it's deeper than that.
Any thoughts?:(