"Now one unit (the real thing being a childhood favorite) is a Lionel "Conventional" 6-28247 Rio Grande SD40T-2"
If I really liked these locos I'd do what it takes to make them compatible with my fleet. Maybe strip out the fancy electronics and wire the motors to an E-unit? You could keep the parts to return the locos to factory specs but I don't worry about re-sale value on things I expect to keep till I die :> .......DaveB
Don't strip it out. I don't know which motor it is, but it may be a dc unit. The board may change the track AC to DC with a bridge rectifier, or diodes to feed the motor.
If you strip it you will just be replacing it with similar, less desirable package choices.