It also has a 3/4" leadscrew. So would this be considered a later model?

I think a better indicator is the thickness of the ways. Older machines
have ways that are 3/8 thick. Newer machines have ways that are 1/2
inch thick. Not sure when the change was made, but I suspect in the 60s
or 70s.

I have a brand new lead screw for a Craftsman 12x36 manual change lathe.
I paid 250 direct from clausing. I will sell for any reasonable offer.

chuck