[Storebror]

1 question

what plane had a turboprop?

The Westland Wyvern did:

http://en.wikipedia.org/wiki/Westland_Wyvern

The Prototype did it's maiden flight in the end of 1946, development started within WWII, so this would fit into "what if" timeline.
Sure enough there's no turboprop which saw front line service within WWII.

Best regards

Mike