Need to clarify a little here. First PS-2 boards are not sold in the Upgrade kits anymore. You may find a PS-2 upgrade kit from a retail store that has one still in stock, but all new Upgrade kits are of the PS-3 variant,
The PS-2 Slave kit was only sold to ASC Techs, because of the extra level of difficulty in the install. Not saying an experienced hobbyist couldn't to it, but that was MTH policy.
There is no PS-3 Slave upgrade kit. If you have an ABA, or Turbine unit with powered B MTH recommends using 2 PS-3 upgrade kits to make both independent units and then run as MU/Lashup.
A PS-2 Slave board will not work with PS-3 A unit and vice versa.
Back to earlier post in this thread, a PS-32 board (which is what is in the Steam Upgrade kit); is a PS-3 Diesel board with modified flash code to work with PS-2 3V files and an adapter board to run bulbs and such. It uses PS-2 3V harnesses. This board can work with a PS-2 slave board. This board with 5V connectors is also the replacement board to repair a PS-2 5V engine. The warning is that this board is slightly wider and taller, and with all the wires at the top. Does not fit in all applications.
Examples are back into Bantam and some RK engines, where original 5V boards were. Engines with small tenders like Climax, PR Atlantics, and some RK engines where speaker is in the front or middle of tender. G
