This is a bit weird. My 1973 pickup has an 18R-C motor, but currently has a Mann W719/30 oil filter installed. During my first oil change (while having an exhaust gasket replaced) the shop didn't have the right filter, said the oil seemed recently changed, so they just added new oil and reinstalled the old filter. Now I'm looking to replace it and find out that this filter is typically found on Audi/VW engines, and the listed filters for the truck won't fit over the tube, or the threads aren't matched. Any ideas how this engine could be using this filter?? I don't know if any mods were done (or if that's possible??) but it looks stock to my untrained eye. there was a decent history of normal maintenance, but no mention or indicator of anything like this. I'll snap some pictures in case that gives a clue as to why this might be happening. Thanks!