So, my guess is that as a possibility, they ran out of some rads on the line. Shift supervisor ok'd a replacement, and those were used. It was noted, and made it into the final version of the parts book.
FYI, my GTX was built third week of October 1969 so Mopar was already slapping 22" radiators in 440 cars. Looking at the radiator list link provided above it shows the same thing in '68 and '69.
