I was at Pep Boys yesterday, cross referencing filters for my 4.6 Thunderbird and had a PureOne, Motorcraft, AC Delco, and Fram all out of their boxes, examining them (they must love me at this store
). I noticed an obvious difference in the overall exterior dimensions of these filters, with the Motorcraft being the largest. The PureOne was the smallest. I wondered if this also meant the capacities of these filters were different, though probably a negligible difference. Any thoughts as to why the dimensions aren't uniform? Is this common with other filters?