This is a 12 bolt GM rear Endhttp://i1239.photobucket.com/albums/...GMLeafPads.jpgAnd 4.10 is the ratio of the crown and pinion (not sure if thats exactally what their called) found inside the rear diffhttp://i1239.photobucket.com/albums/...9/Dcp01464.jpg
4.10 is the components on the right