1. R2LC-08 Radio Board. The board found in many TMCC items between 1999 and the mid-2000's.
2. R2LC-04 Radio Board. A very early version of the board with limited usage.
3. 104E Reverse Unit Logic Board. Used in conjunction with a motor driver. Not sure which version it is.
4. SignalSounds Board. I believe that's a diesel version with horn and bell only.
The labeled numbers on each board are manufacturing date codes (LYtton, WK, YR), and don't have anything to do with the part number or description of the board.
TRW