I bought my model 38 snow blower off Craigslist. It was mostly complete with the exception of the mule drive tension spring and hook, the chute directional handle, and the frame support bars.
I bought the spring off Amazon and made the hook from a piece of round stock I purchased at Lowe's. I made the chute directional handle from a piece of all-thread rod...maybe not the best material to use but the handle doesn't really experience any stress or strain so it should be fine.
The last thing missing...and by far the hardest part(s) to find are the frame braces. I have been looking for quite some time and have decided to make a pair while I continue to look for the OEM parts. Using 1/4" flat stock I drilled and bent the right one. It fits well. It's not as heavy gauge as the OEM part but will have to do for now. The left will be a bit more challenging as you have to accommodate for steering linkage and you cannot use the pedal pivot rod on the left like you can on the right. I'll let you know how that goes.
Please keep in mind that I'm not a professional fabricator and only have standard mechanics tools.