Force 

Sugino Idol kids stoker kit. 125mm cranks and 36 tooth sprocket. Includes chain. Can also throw in a non-drive side dual chainring crank. Asking $75 or best offer. More pics here - https://www.flickr.com/photos/39670213@N06/

bboy314

Do you know the diameter of the seat tube clamp?

Force 

This was used with a steel tandem with a seat tube diameter of about 28.6 mm.