RPO K47, Heavy Duty Oil Bath Air Cleaner, first became available in the mid-1963 model year. This is how it appeared on cars:
At some point thereafter, it also became available for Forward Control (FC) vehicles, and looked like this:
by early 1964 model year, it was also available for AC cars:
Mid-1964, the system was redesigned for non-AC car and also added for Turbo cars:
Design changes were only slightly altered for 1965:
AC car oil bath design was essentially the same as for 1964:
In 1966, the changes in Air conditioning eliminated the need for the separate AC version of K47, so from 1966-69 the 1965 non-AC version was the only one used.