U5 50cc. There was also a U5E which had an electric start. It has a .10 date on it which may mean 1970 which would be about right for this type of step through bike. These are very rare, you see lots of Honda step throughs but not many Yamahas. I have included a picture of a red one that I sold to a guy in California. It is NOT included in the sale. The cover shows a little wear, but no tears or ripsLots of specifications and pictures, including wiring and tool kit pictures. A must for a serious owner. This manual would be helpful and close to the U7 which was the 75cc model.
My shipping calculator does not do well with low weight items. if your shipping to the lower 48 states is more than $9.00 please go ahead and order, email me, and I will rebate the difference on paypal