Airframe Differences

These are the 3 Engines that came on the funks from the factory.

Cowlings

Wing Struts, There are 2 Different Size Wing Struts On the Funks, still gathering info and pics

Cabin Doors -  There are 2 types of doors, The triangle doors and the Flat bottom doors. The triangle doors went to serial #351 and the Flat bottom doors were from #352 on. 

Instrument panels, there are 3 styles of instrument panels that I'm aware of.

Skylights, early planes had skylights which continued back from the windshield to just in front of the elevator trim handle. They can also be installed on later planes with minimal amount of work.

Drop Floor, around serial# 370 the drop floor was introduced giving more legroom.