I use the Ford threaded insert which lets you use a short filter directly to the block. The Ford part number is F1AZ-6890-B. You can Google this PN and find a lot of places selling it-even on eBay. The short filters I have are old ones and not available now. Fram PH35 and Purolator FCO 101. A Mann W77 filter fits well and you can still get them. I have a 90 degree adaptor made by Ford and used on the old Econoline vans but heard that those don’t fit with headers. Eric