A couple of years ago on this site was a rather ingenious gent that built an adatpter that would fit on the OEM filter head so that a better filter could be screwed on instead of the OEM Racor p.o.s. If memory serves me, his adaptation was for a CAT or a Baldwin filter. About that same time many of us were installing secondary filters (either Baldwin, Racor, or CAT) post or pre OEM filters, pick yer poison. Kennedy and Nicktane and others have benefitted, as have those that installed these additional filters. Many of us bought the components and built our own bastardizations of these ideas. BUT, I still believe that IF the original idea of an adapter installed on the OEM head would have caught on, well we would all have one filter, and a much better filter, in the place of these RACOR filters. I know if I had the metal lathe and skills, I would have built one for myself.
Just my ramblings on our workaround for GM's failings.....