Both T-45's in my Cobra have had problems. The first one would stay in 2nd gear SOMETIMES. Sometimes it would, other times it would pop out, but only on a downshift. It also grinded in reverse.
The second one grinds in reverse, and it is stiff to shift to 2nd and 3rd, but only on hot summer days/nights. Sometimes when you come to a light it won't go in to any gear. You have to be rolling and it will go in gear. If I stop and it won't go in I have to shut the car off, then it goes right in gear, start it back up and take off fine. It has ben like this for 3 4 years. I don't want to spend 3K to get the right stuff to fix it. because my next trans is a T-56