The first digit for Chevrolet rallye wheels)is 'K' for Kelsey

The second digit is '1' for Chevrolet

the third digit is the last number of the YR ('9' for 1969)

the next numeral(s) (one or two digits together) represents the MONTH (1 for Jan, 12 for Dec)

The next numeral(s) (one or two digits) represents the day of the month (1 thru 31)

The last alpha characters represent the application (where/when was it used)..

This archive page provides the information:

http://www.camaros.org/suspen.shtml#Wheels