My car came with an original GF-91 TRF Filter on it and since we can not buy these any more I have been working towards recreating the TRF filter identical the factory equipped unit (none the less, Eric managed to score an NOS GF-91 one recently) So I decided since we can purchase the correct ‘style’ filter on e-bay, I needed to come up with a fool proof way to ‘print them’. The old model AC GF-61 is identical to the GF-91 only without the TRF wording. The GF-61-P is also useable however the tube size is 1/16” larger at 3/8” but can squeeze into the 5/16 rubber coupler tubes. Originally, they would have been ‘pad printed’ – basically a roller style rubber stamp that the filter rolled over. I worked with my graphic designer daughter Erin and she designed me a stencil so I can recreate these. Here is the result of our many hours of trial and error! I will be making these stencils available in the classifieds.