Dana Made a bunch of 60s, Hd60s and 70s and Hd70s, I have seen 60s with 3"..3 1/2 and 4" tubes. And 70s with 3 1/2 and 4" tubes. If You don't work with them everyday they can look the same.The covers interchange,the pinion is the same dia. They do cast 60 or 70 on them, but I have seen them badly rusted and unreadable Give Me the Numbers off the Ring Gear, I can look them up and let You know what they are. I Own a Driveline Shop in Pa. Mark Petros, Greensburg Machine&Driveline