The gear box assy. on the 1970 model Apache pop-ups are no longer available.  The gear box assy. listed will fit Apache's from 1970 on.  There was a design change in 1977.  The gear ratio between the drive gear and sprockets was changed.  From 1971-1976 the gears were made with fine teeth, from 1977 and newer the gears were coarse.  This kit will directly replace the gears used from 1977 and newer.  If you have the fine teeth used from 1971-1976 you will have to replace both gear boxes in order to have the proper gear ratio and this gear assy. work for you.  If you have the gears used from 1977 and newer you can replace just one gear box assy. at a time if need be.