The same filter but one is about an inch smaller(pf44). My 2003 Silverado and 2002 Z28 come from the factory with the pf44. I have been using the pf59 size in Napa Gold. Should I be using the smaller filter or the longer.heard that the smaller is better for these engines. You would think that the longer would be better. The Chevy dealer could not really tell me why GM uses the smaller pf44 and if the pf59 would be better for the engines. What do you experts think would be better? Many thanks!