I just finished making greased lightning for our local high school production.  It was based on a golf cart, so it could be driven on & off stage.  It has a wood frame and skin of 1/8" masonite.  I had to return the golf cart, but the body is available, and can be bolted directly to an EZ-GO golf cart without any modifications.  I also have a canvas overlay which was the old, junky greased lightning, removed during a blackout in the song to reveal the hot rod underneath. I'm having trouble attaching photos to this post, but email  me at npkoenig@charter.net and I'll happily send them along.  I am in Richmond, Illinois, about 50 mi NW of Chicago.