Tom, Can't tell from remote. If you apply power conventionally a PS-3 engine will turn on the headlight (can depend on the upgrade) and take a few seconds to start up because it charges the super caps. A PS-2 engine will start up immediately at power on.
PS-3 diesel upgrades are a pure OEM PS-3 upgrade with LEDs.
PS-3 Steam upgrades are a PS-32 board with 10 pin harness. Real OEM PS-3 steam are 6 pin drawbar and a two board set. Tender board and Boiler board. MTH does not sell the upgrade kit with real PS-3 boards for steam. Only diesel.
PS-2 5V and 3V repairs are done with the PS-32 board.
PS-32 board is a base PS-3 diesel board with a different header, and an adapter board that retains original PS-2 3V or 5V harness connections. Drives bulbs instead of LEDs.
When a PS-32 board is used the special PS-32 flash code is used, but any PS-2 3V or PS-3 sound file can be used.
PS-3 diesel upgrades use the PS-3 diesel flash code and sound file to get the most out of the lighting. You could use a 3V SF, but might loose some light function. G