From what ive seen, the TTA uses one of the other pins.
I had both TTAs and TRs at the same time, one day i noticed that the TTA pin was in #2 spot and TR was in #3 spot.
Well its been 3 years since ive seen that.
Possibly you can use either middle pin to excite?
Possibly find someone with both cars and see what they find?
BW