C48 is heater and defroster credit. In most places only shows up for 1967, but at least one set of numbers shows the other years.
From the CRG options page “C48 - Heater and defroster credit. Defroster (and thus the heater) was federally mandated starting in 68. 68 production is export.”
I am guessing it’s only for exports in 69 as well but don’t know for sure.
Grumpy’s 67 L78 was apparently ordered heater delete, no radio and 4.56 gears. Had to be an interesting drive from the Tech Center back to PA in March of 67.
I do not believe everything I read in magazines. The pic seems to show the car with a heater.