Tippy
Yes feel free to PM me with any questions you might have..
As to the date of mfg my records show 1117-C sold on 06-08-68 and on the other side of your number is 1890-C built and sold on 10-01-68 so yes you are correct yours was built sometime late 68.
On your model C the engine would have pivoted it seems someone added the engine plate..this was not a factory addition..