I have the exact same saw. I believe they were made in Omaha, NE. Not
sure of the age, but I think 50 yrs +. You can get blades from an
industrial suppier either locally, or someplace online like
McMaster-Carr or MSC. Some blades I've bought are just a little too
wide and I had to grind maybe 1/8 inch off the back at each end to get
them to fit.

I rebuilt mine when I got it maybe18 years ago, and it still works fine.