Ok, I have been using a Stanley Mitre Box for a while, No.358. Right now, I have two saws for it. They have the same etches on the plates, and spines. Both are Disston No. 4, 11 ppi, 5" x 28" backsaws.
However, at the handle end..
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This one has four bolts, and no cut-away at the heel, the other?
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Has three bolts, and the cut-away heel.
Any ideas as to which is older. Both work great in the mitre box, although the four bolt is a bit deeper cutting.