Vic,
Welcome to the Shopsmith Forum.
Congratulations on your new to you Shopsmith Model 10ER.
The Lathe Screw Center is not at all obsolete and a 4th version is still sold today as part number 505601. Very little has changed to the Lathe Screw Center over the years. It started out with 1/4" set screws which changed to 5/16" set screws then the black protective coating was added and now has a larger diameter base. Not too long ago I used a Lathe Screw Center to make a replacement knob for a dresser drawer.
Just like the Lathe Screw Center many current accessories that connect to the Quill's Spindle can be used on a Model 10ER. Not all current accessories will work on a Model 10E or 10ER though. It is possible some of the accessories with your Model 10ER are newer than the tool itself. One way to tell about the Arbors, Spindles, Chucks, etc. is what set screw they have to attach them to the Spindle. For the Model 10's they were generally set screws needing a 1/8" or 3/16" Allen Wrench. When the Mark 5 came out in 1954 all possible set screws changed to ones needing a 5/32" Allen Wrench. The black protective coating on accessories began in 1964.
As you get to know your Model 10ER better you may have more questions. Feel free to ask them here.
If you want to know more about the Model 10's find the topic
Shopsmith Model 10's What When and Where in the
Community section and at the link below.
https://forum.shopsmith.com/viewtopic.php?t=23647
Lastly, as I always recommend, if you didn't get an Owner's Guide with your Model 10ER you should download a PDF copy available through this Forum site.