Model Railroading > Putting correct SP details/working lights HO models

A local shop has Athearn GP40-2/GP60 units, and I have many SP units from all builders. Can someone put working SP lights on models? Working Mars lights and beacons? Thanks! 

If the units have DCC decoders with 6 lighting functions then all you need to do is add the light castings with led or incandescent bulbs.

If you are not going DCC then miniatronics makes small circuit boards with prewired bulbs you can wire to track and motor circuits.

Richmond Controls offers lighting modules with pre-wired LEDs cast in epoxy to fit into body light holes.
Their Gyralight function is very realistic.
I had used them to put good lights into SP  DC locomotives then when I changed to DCC the Richmond unit worked fine off of the 12 volt headlight output on a decoder iwth a little bit of resistance (maybe about 470 ohms).
The downside is that you get both the headlight and the Gyralight together with F0, the headlight function.