Vintage Radio Service Manual - ZENITH model 5G003Z (Chassis No. 5C40Z) model 5G003ZZ (Chassis No. 5C40ZZ) 4-tube Superheterodyne AM radio receiver. Manufactured by Zenith Radio Corp., of Chicago, IL. Dated 1927. 4 pages. Original old Sams Photofact manual includes schematic, layout, alignment instructions, voltage & resistance test chart, repair parts list and description. This manual would make a sensational accompaniment to your retro audio equipment.