About Us

Since 1993, G&J Diesel has been proudly serving Montana as a trusted leader in light-duty diesel pickup repair, precision engine machining, and quality replacement parts. Located in Billings, our team specializes in Power Stroke, Cummins, and Duramax platforms—providing OE-level diagnostics, expert repair, and dependable solutions to keep your truck on the road and out of the shop.

Our facility includes a full-service engine machine shop, DPF cleaning and testing equipment, and advanced diagnostic capabilities to support both individual and fleet customers across Montana and the surrounding states. We offer precision machining for cylinder heads, blocks, crankshafts, and connecting rods, along with injector testing and fuel system services.

A new online parts division is currently in development to make ordering diesel components easier for retail and wholesale customers.

Built on integrity, technical expertise, and a genuine commitment to exceptional service, G&J Diesel takes pride in delivering professional care and dependable results. Whether you rely on your truck for work or recreation, you can count on our team for the quality, reliability, and attention to detail that keep drivers on the road and out of the shop.