Do you know if you're oil filter mount has the tall tube sticking up from the center? I believe it was, typically, an earlier version but my '74 had it and the standard oil filter would not work. I had to purchase a WIX 51515.
The tube sticking up is the standpipe. If your /6 has one, use the WIX 51515 or the short WIX 51608 if it fits. My research shows a tall and short standpipe. If it doesn't have a standpipe and you want instant oil pressure, then use the WIX 51806 with the built in standpipe. Note the two WIX numbers are close. One day after I changed the oil I started the /6 and got a knock and rattle and the oil idiot light took several seconds to go out. I realized I asked for the WIX 51608 the short version of the 51515. I can go out with the truck sitting for several days and I starts up with with instant oil pressure using the standpipe WIX 51806.
