If you will review a PDF I created titled:
“SHOPSMITH Modifications 10E to 10ER made 1947-1953” you will find a good deal of information.
You will find it in a folder titled 10E & 10ER MAGNA under the link “My Google Drive”
It should help with a good bit of the changes and differences through the years that I know of.
One complicating factor is that users, dealers and Shopsmith themselves performed upgrades on the 10E transforming it to 10ER.
Equally, during the 70 years since the 10E was made, users have disassembled, reassembled even mixed some parts as they maintained and serviced their machines.
In that directory you will find 3 manuals fully restored that are free.
1 The Preliminary manual
2 The 10E manual
3 The 10ER manual
Each of those you may find informative as you seek to define what you have.
Hopefully this will help answer your questions you have not yet considered.
Everett L. Davis