I've got a 1982 Trek 613 that has an Atom rear hub (not a helicomatic hub). Presently, this is a 6-speed. I want to change the freewheel and I am wondering what threads I would be needing. The Trek brochure indicates that the hubs were originally mated up with a Suntour Mighty-6 freewheel. Thinking I would replace the 6 speed freewheel with another 6-speed or move up to 7 speed. Could I look for any Suntour freewheel, like a Winner or Winner Pro or New Winner? How about, Sachs, Regina, etc.? Just don't know what kind of threads would be on a French hub. Thanks for any info.