I found one source on the CRG pages and I think is says ( maybe !!! )
"C" for Cleveland Powerglide
"8" for Model year of car
"M" for August
"10" for day of month
"D" for day shift
My car was built on September 23rd 1967, so if this is correct and the "August" "10" is for August 10th of 1967, then I answered my own quest - do you all agree ? Could this be the original transmission that came with the 230 base six cylinder that my car left the factory with ? ( it now has a 1968 327-300 in it ) I wasn't sure if the powerglide in a six would be the same for the small V8's.