I'm pretty sure it's been said that they don't make a classic of all models, maybe the PF53 is one of them. For my car, RockAuto lists a PF47 (Classic) or a PF47E (Duraguard/E-core).
Yeah, The CL suffix on the regular part numbers gets you the old style AC/Delco with the metal endcaps and center tube.
There is a little reference to it on the official AC/Delco filters web page.