I've always thought the drop towers were more of a "winch" type system as opposed to an actual elevator design like the cable lift coasters.
Not exactly sure what differences are on the actual cables themselves, but generally all an elevator is is a motor-powered winch for the purpose of raising or lowering something on a guided track of sorts.
But even with that general definition, it's not likely in my mind that the motor or cable drum system from one type of ride could be repurposed for another given the different forces and loads at play.