Here's the one I helped build at Texas A&M during the '77-'78 school year. We had two teams of two who built every piece except the castings (more advance class) and the chuck. When we finished putting it together, I got it for material cost, about $42 when the other team members didn't need...
Here's a pic of the backside of the headstock, not sure it ever had flat belts, but there's a groove under the small sheave that makes it look like it may have been on a treadle...
Up close it does look like a slotted tool holder on a cross feed that doesn't pivot, just like you surmised. No graduations on the feed handle. The bearings feel pretty good, I may have to set it up and see what it'll do.
This is an old lathe my dad took in trade for some work years ago. Pretty interesting piece, no info or tags on it...Thought ya'll might like to see it.
I found you all when I googled a small Craftsman lathe I saw in an auction flyer. I ended up winning it. It's a Model 101, in great shape and I just made my first shavings. Thanks for the help you already provided and I'm looking forward to hanging out with you all!