You got me wondering about the PF29 versus the PF25. Since my AIM is missing the part numbers for the filter, I looked in some of the literature that I received from the GM Customer Assistance Center. Although the part numbers are not listed it states that the L6 engine had a "full flow, throw away canister" versus the V8 which had a "full flow, replaceable element". The originals of those were white with blue lettering. The GM part number for those was 19187300. They were white with the red AC logo.