Scoob37,
At serial number 37871 it would have either an ER prefix for the eastern plant or R for the western plant. The prefix E had been replaced with ER by that serial number for the eastern plant. If it has the ER prefix it would have been made in early 1951. If it has the R prefix it would have been made in 1950. The serial number were not running evenly between the eastern and western plants. Serial number ER40908 and R53198 were both made in April 1951 when a change to the Headstock and Carriage occurred.
For more on the Shopsmith Model 10's check out the topic Shopsmith Model 10's What When and Where at the link below.
https://forum.shopsmith.com/viewtopic.php?t=23647