I have a pair of these my Grandfather had. Problem is, the date codes are nothing like Klein describes in the above linked contest page. Near the bottom of the handle, on the inside surface on one handle there is a very clear, stamped into the metal, "O-4-37" while the other handle has a single "O" stamped in it.
The logo is as described except the text is all vertical, but wrapped around the circle, rather than the text being arranged radially around the circle. The beginning M and the ending S in M Klein & SonS are extra large.
The outside of the jaws are rounded like they describe as being the newer smoother "new england style head".
Klein may not be aware of all of the detail differences in their older products.
My grandfather did odd work and wired houses in NE Missouri when rural electric was coming into the area (after losing his job with the Walbash RR), and he moved to the west central part of MO about this time and became a postmaster, so these pliers didn't get used alot, and are in fairly good condition. (I recently visited my grandparents grave site, for the first time since my grandmother was buried in 1961. GF died about ten years earlier, before I was born)
Klein needs to up the ante, my would not be for sale for $2500 cash and $2500 tools if they were the oldest due to sentimental reasons. If I had found them at the flea market, that might be another story.
Charles
(But still VERY cool!)
