Hello again cabboy,
It seems that to know if the (R) in the body number is from Regina, that vehicles Model Serial Number needs to fall within Regina's beginning and ending assigned Regina series numbers. Do you have the model serial number by chance?
Still don't know what CS stands for. It's Canadian, it's a Sedan, Completed Sedan, Can't Say. Here is another post I came across:
This data is off a very rare Regina car:
GENERAL MOTORS
of CANADA Limited
MADE IN [ MAPLE LEAF] CANADA
OSHAWA WALKERVILLE REGINA
MODEL SERIAL NO
UNIVERSAL 458639
ENGINE NO 269801
FISHER BODY
BUILT BY
GENERAL MOTORS OF CANADA LTD. OSHAWA
CORRESPONDENCE PERTAINING TO THE
BODY MUST BEAR THESE NUMBERS
JOB NO. 30557
BODY NO. CK 227 R
Note the 'CK and 'R'!! Now, the 'R' suffix indicates presumably 'Regina Plant'..now we know that this ia Regina car because the serial # fits into the Regina series:
# 457001 to 462438
However what does 'CK mean? In 1928 Oshawa used 'K' for some bodies, but I suspect that it means 'Completely Knocked [down]'. Regina did not have a body facility in 1929-30, and 1931 when it was open but it did in 1937-41 after it re-opened for the second time [note opened once, closed, re-opened, closed, then re-opened, then closed for good]. All bodies were imported it seems as components from Oshawa and then assembled.