MTH PS-2 couplers have patent writing on them and PS-1 do not. If you have a PS-1 and PS-2 engine look at the coupler you will see the difference.
For this conversion, your engine tender needs the external harness and wiring inside of it. If the engine did not come with it you have to add it and splice into the original Reverse Light and Reverse coupler wiring. SO that is more involved. G