As an NFPA member, they set the rules, the insurance companies enforce the rules thru listing agencies. The product is listed with UL and FM, not the path to market.
If the product is listed with UL and/or FM to meet the requirements of the appropriate NFPA code, then the product is listed by the manufacturer, regardless if you buy it from a catalog or a store. However if the product is listed by the distributor, then it carries the distributors markings and/or unique product identifier. This is the only method in which a path to market can be listed.
regarding chassis, GM, Ford, international etc still make commercial chassis. Other manufacturers such as Sterling, PACCAR, Volvo, Diamler, Spartan, KME, Pierce, E-one all make commercial chassis for fire apparatus.
