My Enco 92010 is a 12 x 24" from '82, had the same problem. I bought a Grizzly part from a G9249, a lathe that's not made anymore but they still had the part when I needed it, couple years ago. There was no hole through the shaft in the Griz part, so I drilled it. Diameters and gear tooth number/profile were correct. There was one other length dimension that was a bit off but I modified it to fit easily enough, works perfectly. Here's the Griz part installed:
BTW I have the original user manual and parts list for mine, and it covers several sizes including 10 x 24" and 12 x 36". The part number for the spur gear is the same for the 10" and 12" swing models.
Sorry I don't have a record of what that length difference was. I still have the original Enco gear and could measure it if anyone's interested, but I am not going to take the Griz replacement back out to measure it for you! Sorry I'm not that nice a guy.
Here are my notes that I made back then:
Enco part # is "92010 - 246", Name = "Gear"
LAM part # is "3C-6", Name = "Transmission shaft". (mat'l spec listed as "S 45C")
Jet 1024 part # is "3007"
Tida part # is "TD-4D-12"
Grizzly G9249 part # is "P9249336", name = "GEAR SHAFT 16 X 116T"
I bought it, one dimension was slightly different but I made it work 100%