What would cause an Automatic transmission to fail while driving at a constant speed?

I may not have worded the question very well. Okay, but here's the deal. I was driving to college on the Interstate, going 80 MPH, in a '98 Mercury Sable, 100,000 miles on it. While I'm driving it, it fell out of gear, so I pulled to the side of the road and parked it.





I can start the car just fine, but if I attempt to change gears, there is no response. I can move the gearshift just fine, but nothing happens in any gear (P, R, N, D, OD, or 1).





We had it towed by our insurance company to Mr. Transmission. After doing some research on the company, I don't trust them to do any work on my car, especially after the response we received.





They told us they'd have to do a tear-down inspection, and we authorized that, but now they're telling me that six different parts have been destroyed, and to rebuild the transmission, it will be around $2,500.





Is it likely that much damage has been done in this amount of time? We're taking it elsewhere regardless. Thanks!|||When was the last time anyone checked the tranny fluid??? As the repairer said, it could be anything especially with 100,000 miles on it A 98 is a little old to be traveling 80 mph...At this point, I would look into a used tranny out of the bone yard....but even so I'd dump the car..it's cheaper to buy another crasher and drive it for a few yrs.. but I think you ought to slow down and also start maintaining your cars better|||junk it... move on... not worth fixing... salvage yards or overflowing with the heaps