I installed a new inner chaincase from AN on the 74 850 I'm rebuilding and carefully got the center stud shimming right. While doing the oil hoses and horn, I noticed that the swingarm appeared to be touching the chaincase. A piece of paper will fit between them except in one spot. Of course, I have the entire primary done. It would be easy to relieve a little from the chaincase before installing. So, if you're installing a new one it would be good to check before finishing the primary.