U4127
That's a model U4127 and was the first of the plastic Convertible series. Those made their debut in 1977 or 1978, I believe... and were made for a good number of years. I've seen a TON of that model over the past few years, still out there and in service.
In my opinion, (if the base of the machine isn't cracked--the fan chamber), they were excellent performers. I used one for a while as my daily driver and was very pleased with it. Lightweight, easy to use, simple. And I like the color combination.
~Fred