fender usa 62

Please help ID an old Yamaha?
I am looking for a little help to ID an old Yamaha (probably between 50 & 90cc), my best guess from the info I have (tail light lense and basic style) is early to mid 1960s. It has a “J19” stamped on the frame and the serial number is “M3-2064??”. Any information on this bike would be helpful. I have not yet found anything on the net to really nail it down. I mainly need service info, specs, etc. I would like to find some sort of manual for it. I am not even sure if it was originally sold in the USA or if someone had it shipped in.
I have put up a few pictures on my web site, maybe they will help.
http://jimmccall.com/yamaha/
It looks a little like a 62′ Omaha Trail50.
http://www.e-tabitha.com/images/Gingerale%20Photos%202/Omaha%20Trail.jpg
It might be a different year of the Omaha Trail50 because the front fender and lights don’t seem to match a 62′. But that is the best match I have found. The 2nd seat is a nicely done aftermarket and probably not factory.
Looking through Yamaha product history, it appears to be an incomplete “U5 Mate”
http://www.yamaha-motor.co.jp/global/product-history/mc/1960/index.html
“This was the first version of Yamaha’s best-selling Mate business-use bikes. The name “Mate” was the result of a public-participation naming contest. This model immediately won unprecedented popularity for the high product quality deriving from its combination of advanced features like the revolutionary Autolube separate lubrication system for the 2-stroke engine, automatic centrifugal clutch and its single-unit “U-bone” frame running from the steering head to the rear fender. The TV commercial with its catchy, upbeat music also became a big hit.”
Hope this helps some, still doesn’t look like Google pulls up much infor, but I’m certain there’s an enthusiast site out there Somewhere.
Cheers
L’Arc~en~Ciel farewell Bass