The Filter was in the cockpit above the left side rudder pedals behind the panel.
But in your Cessna it could be in a slightly different position.
The item is made by Rapco and is about 4 inches long and 3 inches in diameter. Looks like a cylindrical concertina of paper.
Easy to fit, jus unscrew the two facing plates, disconect the tubes and refit new one. A five minute job, except in my RV6 you need to be very small and slim to wiggle your way under the footwell. In fact I just took the seats out so I could lie in the aircraft stretched out.