Hello, I just picked this up last week and there's no data plate in the normal area. I think I located the serial number stamped into the right side just near the end on the floor board plate. Looking online, I see Yales with the unique 3-post safety cage but find different model numbers such as KG51T-20H then another one that also looks the same with model L51AT-400F.
Here's what I know... single speed manual transmission, single stage lift cylinder (about 120"), cushion tires, I believe a Continental F124 engine. # stamped is F074474.
Links to photos...
https://postimg.cc/zVM7VWTS
https://i.postimg.cc/BnhwrPPv/F2.jpg
https://i.postimg.cc/3wdbYr2F/F3.jpg