Craig wrote that the '67 parts book basically tells the techs to make a new one themselves if for some reason they need replacing. I assume that's for both sections.
On your car heater hose clamps have been changed. Clearly there was some regular maintanence. So yea I gues the filter change would be expected.
I guess what surprises me is the filter location. There was a bulletin or master tech about locating the filter vertical. I thought it was early 60s. lemme look.