There is not a synchro for reverse so it will always not want to engage sometimes. If you roll the car forward a hair will it go in? Try going 5th to reverse. Those are what I have to do with my T-45. You could check the fluid. Someone else might tell you it is something that is an issue and id go with them and check that out. Even in my new T5 behind my 289 it has troubles going into reverse. The fix is letting it roll slightly or 5th then reverse. Good luck!