A parts cross-reference guide is used in the automotive industry to easily find interchangeable vehicle parts. Online access to parts cross-reference guides are available at ShowMeTheParts.com and ACDelcoTechConnect.com.
For example, searching ShowMeTheParts.com's catalog for a 1998 BMW 318IS air conditioner clutch and compressor returns a list of nine results with parts from three different aftermarket manufacturers, including both new and remanufactured options. Selecting a part number from the list elicits a pop-up menu that contains a picture, specifications, and applicable BMW makes and models for that particular part. This site also offers a smartphone app.
On the AC Delco website, hovering over Parts Catalog reveals a drop-down menu that allows a search by part number, vehicle make and model and also a competitive cross-reference searchable by part number. Searching by make and model for 1977 BMW 320i L4 spark plugs returns a list of two products; however, when View List is selected on this website, a pop-up windows reveals the number of vehicles these particular spark plugs can be used in.
AC Delco's site operates in the reverse order of ShowMeTheParts.com. Show Me The Parts takes the vehicle information and relates it to many parts, while AC Delco uses the part information and relates it to usability in many different vehicles.