Forest Service Lock by Yale

[wvanauken]

I have a Yale Forest Service lock that looks to be quite old. I states on one side of the lock "Made For" and then in big circular letters "Forest Service" with an embossed pine tree and the letters U and S on either side of the tree. See attached pics. It is a beauty. The key doesn't look like the original. If any of you have any info on this i.e. age, worth, history, etc., I would greatly appreciate your input. Thank you.