As to David's thing tranny....its a Type1 tranny case, but the
major difference between the thing tranny and the bug tranny is
the final drive ratio and I believe the 3rd & 4th gear ratios...

I am certain on the final drive ratios however....the Thing revs
higher at speed than a bug will. A bug tranny will fit the thing
assuming you change the CV joint cups from the thing tranny
to the bug tranny.

BTW...little known fact...the CV joints and axle shafts on the
Typ 181s are the same as on the Porsche 924 (non S model).

Ric