Okay, I guess I have to chime in with the details. The Shopsmith Model 10E was the original 5 in 1 tool made by Magna Engineering Corporation, the company formed to make it by the inventor and his partners. As changes occurred and at some point they decided to call it the 10ER. Looking at the three versions of the Logo/Serial Number plate the 10E and ER are the same except the model number on it and of course the serial numbers. When they changed to the 10ER, I believe instead of redesigning the Logo Plate to make 10ER fit they simply changed 10E to ER. The later version of the Logo/Serial Number Plate has 10ER on it. The E, ER and R prefix for the serial numbers are a different matter.
Mark V 520 S/N 09-11-01 completely upgraded to Mark 7, with all SPT's & more.
Model 10ER S/N R64000 first one I restored on bench w/ Shopsmith metal ends & retractable casters. Has Speed Changer, Model 4E Jointer, Jig Saw with lamp, a complete set of original accessories & much more.
Model 10E S/N 1077 oldest one I have restored. On bench w/ Shopsmith metal ends & retractable casters.