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.To be fair, I don't know if that's the part at all related to this particular issue, just that it seems elevator components on various rides are usually the main issue for large parts biting the dust and needing replacement.
But could did Intamin design the lifts so that theoretically they could take a spare for I305 and use it on Drop Tower or Eiffel Tower? My guess is probably not.
That being said, I'm sure Intamin tries to use similar parts as much as they can but even in doing that, things are so drastically different. I also think that Intamin likely stocks a lot more than people give them credit for. I still continue to wonder how much A3 is actually doing for all of the CF chain..... I wonder if they expanded and when CF says there is a delay in the part it's just that it's taking A3 longer to reverse engineer and produce a replacement than it would if they just ordered the part from Intamin.