I bought this Disston No. 9 saw equipped with the optional gauge a couple of months back. This particular saw was made, best I can tell, some time around 1877-1879 or so. It has a taper ground 0.025" blade toothed 12 ppi filed crosscut with a 16" toothline. It appears that all of the hardware is original or at least of the correct period.
Attachment 372128
Here's a closeup of the medallion for the aficionado's.
Attachment 372129
I decided to recreate this saw so today I knocked out a batch of blades and the gauge attachment. Here's the original and my blade with hardware and gauge.
Attachment 372130
And the other side.
Attachment 372131
The back will be heavy brass and I'll likely tooth this blade at 13 ppi. The blade, like the original, is 0.025" taper ground.