1975-1976 CHEVROLET MEDIUM DUTY HEAVY TRUCK SUPPLEMENT Body, Chassis & Electrical Service Manual [eb11290R] 
This manual covers body, chassis, mechanical and electrical. It has sections on suspension, driveline/axle, brakes, engine, transmission, body, accessories, etc. This book includes wiring diagrams. Published by the factory, to provide information on diagnosis, service procedures, adjustments and specifications, there is none better. It is loaded with diagrams and illustrations to show you how to disassemble, repair and reassemble the various components and frequently gives troubleshooting information.