OEM is an acronym for Original Equipment Manufacturer. This is a company that supplies components for a product that another company sells. For example, your Datsun 1200 (Nissan's product) came with Bridgestone tires (made by Bridgestone). So Bridgestone was an OEM to Nissan. Or converserly, since Nissan sold many tires for Bridgestone, Bridgestone would consider Nissan one of their OEMs. So the term is used in both directions.
For more details, see Original Equipment Manufacturerᵂ.
Support for OEM parts
Generally speaking, support and warranty of OEM parts is covered by the manufacturer of the finished product. So the Clarion radio in your Datsun was warranteed by Nissan or by the dealer your purchased the car from. You wouldn't go to Clarion for help if the radio didn't work.
The big exception to this is tires: In the USA at least, tires are warranted separately from the rest of the automobile.
Part Supplies to Nissan
Your Datsun 1200 was built with many parts supplied by companies other than Nissan. Some notable Datsun 1200 OEMs included:
- Hitachi, a business partner with historical ties to Nissan
- Carburetor, optional radio, and "H"-series differentials
- Bridgestoneᵂ, Japan's premier tire supplier
- Tires
- Mitsubishi
- alternators, distributors, starters
- Tockico and Atsugi
- Brake and shock/strut suppliers
- Clarion (car audio)ᵂ
- optional radio
- Ichikoh
- Ever Wing
The OEM system is used by all automobile manufacturers.