Our service department provides many options for your overall needs. Whether you need on-site one-time repair or a full scale service and maintenance program, our team of highly trained technicians at Harmon Truck Service is there to help. Our service department has extensive knowledge of all makes and models. Likewise, our technicians undergo constant training to remain on top of current technology. Additionally, our shop offers a complete selection of OEM Specialty Tooling and Software with state of the art testing equipment. Therefore, you can trust us to get work done right the first time.


Contact our Service Department

1-573-468-5138 or by email

Our company offers many repair services for the On-Highway and Off-Highway Diesel Industry:


We offer top of the line laser alignment and can handle alignments on class 4, 5, 6, 7, and 8 trucks, trailers, all classes of motor homes, coaches, and emergency vehicles.

Engine Conversions

Are you happy with your truck but not your engine? Harmon Truck Service offers many different conversion options for your truck.

Hy-rail Service & Repair

FRA inspections, repair, alignment, adjustment, and maintenance services for hy-rail equipment.


We offer a full array of coach/bus service and repair options so you can get back on the road faster.

Construction & Heavy Equipment

In-house or on-site service and repairs for your construction and heavy equipment. Call for details.

Rehab & Accident Repair

Whether you’ve had an accident or want to bring that old worn-down unit back to life, we can help.

Engine Repair

We offer up-to-date, premium diagnostics and repair for everything from the smallest concern to complete engine overhauls and replacements. Both OEM and after market engines and parts are available for CAT, Cummins, Detroit Diesel, International, Mack, Volvo, and more.

Transmission Repair

We offer in-depth transmission diagnostics and repair. We stock  Meritor, Eaton, and Allison components.

More Services …

  • 24 Hour On Call Service
  • DOT Inspections
  • Heavy Duty Engine PM
  • A/C Services
  • General Truck Repair
  • Agriculture Equipment
  • Government Sales
  • Military
  • Off-Highway Trucks
  • DPF Diagnostic
  • Heavy Duty Engine Repair:
  • Detroit
  • Cat
  • Cummins
  • IHC
  • Mack
  • Volvo