GMC FM340 Parts & Accessories

GMC FM340 Parts & Accessories

The GMC FM340 is a vintage medium-duty commercial truck from the mid-twentieth century GMC commercial lineup, used in heavy vocational and fleet applications where the FM prefix designation indicated a specific cab and chassis configuration within the broader GMC medium-duty truck family of that era. These trucks were purpose-built work platforms serving municipalities, utilities, and contractor fleets that needed a commercial-grade chassis beyond the capacity of the standard light-duty truck lineup. Parts for the FM340 and related vintage GMC commercial platforms are primarily found through specialty classic commercial truck suppliers, old truck swap meets, and the restoration community that has preserved original and rebuilt components for these low-production platforms. Cross-referencing with other period GMC commercial truck platforms is often the most effective strategy for finding mechanical components that were shared across multiple model designations.

Popular Upgrades

Electronic ignition conversion kits from Pertronix are among the most practical upgrades for any vintage commercial truck in regular service, eliminating the points-and-condenser maintenance schedule and providing more reliable ignition timing across the RPM range. Carburetor rebuild kits or replacement units from Holley or Edelbrock in the correct size and flange configuration address the fuel delivery degradation that accumulates on a carburetor that has sat without use or accumulated decades of service. Brake system refresh kits including wheel cylinder repair kits, master cylinder units, and brake shoe sets from the vintage truck parts market return the hydraulic brake system to safe operating pressure and consistent pedal feel.

Performance and Handling

The FM340's commercial-grade chassis uses leaf spring suspension appropriate for medium-duty payload ratings, and replacement spring packs, U-bolts, and spring eye bushings restore the original load capacity and ride floor height on trucks that have sagged from decades of heavy use. Steering linkage wear is a common maintenance concern on vintage commercial trucks that have accumulated high mileage in steering-intensive commercial service, and rebuilt or replacement tie rod ends, drag link components, and steering box units address the play that makes a worn commercial truck difficult to control precisely. Cooling system refresh with a new thermostat, radiator hoses, and water pump unit is a practical preventive maintenance step on any vintage commercial truck being returned to active service after a period of dormancy.

What does the FM designation mean in GMC truck nomenclature?

The FM prefix in GMC's mid-century commercial truck naming convention indicated a specific chassis and cab configuration within the medium-duty lineup, with the number following the prefix denoting the payload or GVW class of the truck. GMC used a series of alpha-numeric prefixes across its commercial lineup of this era to differentiate between conventional cab, forward-control, and chassis-cab configurations at various weight ratings. Understanding the FM designation requires consulting period GMC commercial truck literature, as the naming conventions changed across production decades and differ significantly from the alpha-numeric system used on later light-duty trucks.

Where can restoration parts for rare vintage GMC commercial trucks like the FM340 be found?

The most productive sourcing channels for FM340 parts include specialty vintage commercial truck parts dealers, old truck events and swap meets where these platforms are represented, and the online auction and marketplace listings maintained by collectors who specialize in mid-century commercial vehicles. Mechanical components including bearings, seals, gasket sets, and brake hardware often cross-reference to other period GM platforms produced in larger numbers, making those components easier to source than body-specific or chassis-specific parts unique to the FM340. Joining online forums and communities focused on vintage GMC commercial trucks is the most reliable way to connect with the specialized knowledge and parts network that supports these low-production models.

Why These Parts Fit Right

Parts listed for the GMC FM340 are verified against the platform's specifications with cross-reference notes to related commercial platforms where applicable. Engine and configuration fitment is clearly noted to guide correct part selection on a rare vintage platform. Most in-stock parts ship same day or next business day.

Related resources include the exhaust systems collection, the suspension parts catalog, and the air intake systems section.