Roger: I just sent you an email since I have to leave shortly. My TIU's are numbered TIU 2, TIU 3, TIU 4, and TIU 5. The one that works my regular layout is TIU 3 for track 1 and track 2. The others work my yard in another room, my subways on another level, and my large scale from the ceiling.
Rich G.