Speedometer manufacturers are just a sub-field of the automotive industry. They work closely with mechanics, automobile manufacturers, and car parts suppliers. The speedometer manufacturers fabricate digital and dial-based readers, which they then sell in bulk to different mechanic or parts companies. Any person working within one of these factories needs a GED, and on-the-job training. Line employees need to inspect and help assemble each speed gauge, making sure that it is ready for whatever truck or car model it is going to be installed in.
Vehicle manufacturers are a major part of this industry. They are also a major buyer for speedometers, if the speedometer fabrication is not already a subdivision of their factory. These companies are the ones to actually assemble motorcycles, dirt bikes, cars and trucks in their entirety. Any employees working here need at least a GED, and will be trained on the specifics of their jobs. They also need to determine which type of gauge to install in which car dashboard, for instance electronic versus the dial.
Mechanics, on the other hand, need extensive training, and certification. Many of them enroll in trade school, and then undergo an apprenticeship before they are able to work independently on any vehicle. For example, when a mechanic is repairing a broken speedometer, he or she needs to know that it is connected to the transmission through cables connected to gearing near the tail shaft. Mechanics, aside from their training, often have connections to parts suppliers. They can get both new and used replacement speedometers cheaper than most individuals, making it cheaper for their customers in the long run.