Transmission Problems with 98?

I drove out to my sisters the other day. When I went to leave I went in reverse then put the car in drive it wouldn't go forward. I tried 2nd and 3rd no go. When I tried 1st it whined and sounded like I had the park brake on but wasn't on. My 98 3.8L has about 120,000 miles on it. The transmission guys are putting a new transmission in it. Could it have been something else? Also they want to replace the ball joints. Do they wear with this many miles?

If it won't go forward and it is full, there are serious internal problems, the ball joints can wear at anytime depending on roads and driving conditions, look at them when they have it on the lift and see if they are loose.

I had a Nissian Sentra which gave me warning that it was going it started to slip putting it in gear. This gave me no warning. Is there something I should be looking for the next time? Hopefully there is no next time.
Our roads here in in Brandon, MB have been in terrible shape so I knew they may have been worn. They replace the bottom ones. Thanks