Did a search on this board and didn't find anything pertaining to this. I recently read this article in the July/August 2014 issue of ACDelco TechConnect. Here is the source: http://acdelcotechconnect.com/pdf/newsle...-Newsletter.pdf "ACDelco oil filters PF48 (GM part number 89017524) and the Durapack version, PF48F (GM part number 19167894) are transitioning to a new design that offers improved performance. The new part numbers are:PF48E (GM part number 19303975) and PF48F (GM part number 19303974). This will be a rolling change and the old version will not be available once stock is depleted. The redesigned PF48E filter performance improvement relates to the relief valve design. The PF48E has a compression spring loaded nylon poppet that outperforms the current valve design. In addition, the collapse strength of the filer has been increased by 25 percent due to the perfectly round nylon core. The filter media also is no longer potted in adhesive, which blocked filtration area." I did a search for PF48E and found this discussion: http://www.gm-trucks.com/forums/topic/160719-pf48pf48e-redesign/ Looks like the PF63 will be replaced with an E-core version also. I'm not here to debate E-cores vs. classic ACDelco filters. I just wanted to give people a heads up if they prefer the classic construction they may want to stock up.