Keen Kutter hatchet date???

[Trent Rock]

I bought this a few months ago
I was expecting the BIG/heart shaped KEEN CUTTER logo/stamping
At first I thought it might have been a fake
I found a Keen Kutter sharpening steel on Ebay that had the same stamp
Any idea as to the date range?
Anyone have any good links regarding Keen Kutter hatchets? or Keen Kutter history in general?
It's not like I'm losing sleep not knowing the date or anything
I was just sorta curious as usual
I figured this forum need some content to liven it up a bit

Here is the pic of the steel on ebay===>