I haven't found any markings on this part, and I did look for it in your catalog, but didn't find quite the right part.
The Windows are by ALUMAX, and were installed in 1997. Needless to say, the warranty is out-of-date. I have tried several window companies and they refuse to try to locate parts and insist on installing new windows. There is nothing wrong with the window or the sashes, and I'm totally infuriated that these companies think that because I happen to be in my 70s, I'm gullible enough to buy into their schemes. I know a replacement window is several hundred $$ and a pivot lock shoe is going to be less than $10.
The part measures: Height-2inches. Width-1 1/2 , Depth-17/32. I'm not sure what the part above it is, but that is also broken.Any help would be most appreciated, especially to foil those window companies.