Looking closer at your picture, I do see there's a difference, I've never seen that board. This looks like an improvement over the previous board, it has a 555 timer on it. It actually should be pretty easy to figure out the wiring, the pin on that three-pin block that goes directly to the anode of the diode is obviously track power. Another pin on the block is ground, that will go to one side of the fan and also the negative side of the largest capacitor. Finally, the 3rd connection will be the chuff switch, it'll be wired in parallel with the chuff going to the Cruise Commander.
Note that this board can NEVER be paralleled with anything connected directly to the sound board as the sound board chuff input must be TOTALLY isolated! The chuff MUST go to something like the Cruise Commander or R2LC and the audio chuffs triggered by the serial data stream to the sound board.
