Welcome, you have a very nice looking 201D3 (I think that is what it would be considered). External motors on 201 machines aren't found often in US.
As you have discovered the C serial numbers are very hard to date. There have been some lists which were said to be wrong. There is post on another forum that indicated that the
"C 3333118 is in a batch with 35.000 others. Dating is Christmas 1937." Also on that forum it indicated that the badge on your machine started about 1933. According the the ISMACS comprehensive model list, the 201 didn't come about until 1935. So it might be that the closest you may come to the date for your machine is 1935-1937. Also something to note with the US and Kilbowie serial numbers date is the date the numbers were allocated, not the date they were actually made.
There are manuals for a later 201K at
https://www.manualslib.com/manual/68...nger-201k.html and
https://www.manualslib.com/manual/36...nger-201k.html