Help identifying mark.

[Jimmy Langford]

I dug this up awhile ago and have been meaning to make a post on it. I tried looking it up in Glassbottlemarks.com but didn’t seem to get anywhere with it. Does anyone know this mark ?

 

[PlaneDiggerCam]

It could be Underwood Glass Co. Circa 1956-1979? Pretty hard to tell because there are a couple manufacturers that had U as a mark.