Atkins bucking saw

[sandersdwa]

Came across this Atkins bucking saw and am wondering which model it is? I have other Atkins bucking saws but this one has me stumped. It measures approx 0.089" at the tooth and 0.061 along the back. It is segment ground and I found it has a straight back. Oddly enough, I put my Atkins 51 against it (see pic) and found out the Atkins 51 does not have a straight back! News to me! Thought it was a 361 but I have a 361 but this saw has a wider tooth spacing and is much more stiff than a 361. It has the same etch as my 361 and what is left of the etch looks like "No 86" but I don't see an Atkins model of that number. Then there is the "X" mark below the model number. Anyone have any ideas?