You could be the owner of this very unique Tokheim wheel/ 5 speed derailleur system.

What follows was taken from "Calvin's Corner", a blog on the Park Tool website. A detailed description and video of a working model can be found here

Made in Fort Wayne Indiana in 1974. In this system the chain is not derailled in the sense that occurs on the multi-cog shifting bikes. Rather, the chain is lifted up and away from the hub to one of four possible diameters. The chain does not move sideways over different cogs to do this. A series of blocks called "drive segments" are be moved in and out of a rotating plate or disc by the shifting mechanism. A twist grip shifter has five possible detentions. The fifth gear is a regular sprocket, and the other four gears use the block system. The mechanism to accomplish this was called the "interposer", a great technical term in its own right. These were commonly found in Huffy bicycles from 1974 to 1975.

Item Condition: It has been previously used, and from some pictures we've seen, may not be completely intact. The shifter is not available from us. The wheel has 36 spokes, and the tire size is 26 X 1 3/8. If you have a broken unit, this may help restore your retro project.