2001 Century trans issues!!!

My dad has a 2001 Century that started out shifting hard, like when you'd go from reverse to drive it would jump. He wasn't smart and ignored it. It started slipping and not wanting to go up hill. It began to leak fluid. Got the lines replaced, he was driving home and said he had to put it in 3rd to make it go because it quit moving in drive. Before he takes it to the garage I was wondering if anyone could give me a heads up on what it could be and what it might cost to fix. I appreciate any help, thanks

The trans needs an overhaul, 1500.00 here in NYS.

Thanks for the response. I'm not in NY and can't see putting that much into a car that the trade in value is probably only $2000 or so at most

Thanks for the response. I'm not in NY and can't see putting that much into a car that the trade in value is probably only $2000 or so at most


$2,700 in Washington. Wish I was in NY.