Maybe Andreas Rhude will chime in here. He's a Thompson Boat expert and may have some insight as to the numbers.
As I mentioned, no records exist and Thompson canoes with a serial numbers are few. I have seen a couple that have had aluminum name tags with a serial number on them. If that is what you have, I would say you would have a canoe that was built in the latter years of canoe production. If this number is stamped into the wood somewhere on the hull, it may be an asset or identification number for a particular owner..ie... CS= Camp Silverthorne asset number 386.
Again... photos may help.
Dave