Spark plug cross-reference guides are widely available for download from multiple sources on the Internet, including sites such as Sparkplug-Crossreference.com and a variety of online auto supply companies. The type and brand of spark plug determines which site has the appropriate cross-reference guide.
You need to know the brand and part number of the spark plug, which can usually be determined by reading the fine print on the part. Once this has been determined, the easiest way to find an appropriate cross-reference guide is to enter the brand and part number into a database such as Sparkplug-Crossreference.com. Upon entering the information, the website returns a list of replacement spark plugs arranged by brand and model number.
To download a printable reference guide, sites such as Jegs.com offer replacement parts. On Jegs.com, find spark plugs in the main menu under the Ignition & Electrical category, where Spark Plugs is one of the main categories. Clicking on this category brings up a list of the different types of spark plugs that Jegs.com offers. If there is a spark plug reference guide for the brand, as is the case with Accel Copper Core Spark Plugs, the brand's page provides a link to a downloadable PDF.