Manuals – Parts Catalogs

Bentley Publishers (lots of makes, American and Import)

Helm, Inc. – ( American and Import )

Binder Books – Manuals/Parts catalogs/Brochures for International Products

Hemmings Motor News

Parts Avenue LLC (parts, info, manuals… etc..)

The Old Car Manual Project – old car/truck manuals – online and free

Old Online Chevy Manuals – Information for the Pre & Post-War Chevrolet Passenger Cars & Trucks

GM Parts wiki

a site dedicated to GM parts numbers, scans of old parts books, along with photos of the parts and their boxes/packaging.