Well, it's 1:1 for the connectors, the pinout of the various connectors is the same. But...WAIT!
You have to remove the shells from the toasted 5V board and the 3V board and slide the black shells on the 3V board. The connectors are pinned the same, but they are NOT compatible physically.
It's best to heat up the plastic a bit on them before trying to slide them off. Also, be VERY careful on the 3V board not to damage the board getting the connector bodies off, obviously it doesn't really matter on the 5V board.
You will need to replace the 16 ohm speaker with a 4 ohm speaker as the 3V board uses the lower impedance.
Finally, you will NOT use the 9V battery or harness. I recommend a supercap replacement to solve that problem.
Hey Pete,
I am assuming you have a new upgrade kit with the PS3/2 stacker board. The board from this upgrade kit is designed for 3V plugs. Your 5V plugs will be a little off. MTH does make a stacker board with the 5V connectors, but is not included in the kit. You might be able to exchange it for one from MTH or a service center. Also, the speaker must be changed as the OHMS from 5V-3V are different, use the one in the kit. Lastly, there is no need for a battery, as the PS3/2 boards have the Super Caps built in like the standard P3 boards.
That board is a PS/2 3V board, it's not the PS32 board, so he needs a battery. Also, MTH hasn't had the stacker boards with the 5V connectors for many months, the procedure I described above is how I use the PS32 when I have to replace a 5V board.