FAQ — Diesel Parts & Fitment

Fitment & Compatibility

How do I know if a part fits my truck?

Every product on our site is organized by year, make, model, and engine code (e.g. "2017-2025 6.7L Powerstroke" or "2004.5-2007 5.9L 24V Cummins Common Rail"). Browse the collection that matches your truck, or use the search bar. If you're between generations or unsure, email us with your VIN.

What's the difference between FASS Drop-In, No-Drop, and Titanium Signature?

Drop-In Series replaces the OEM in-tank pump and stays inside the fuel tank. No-Drop Series mounts to the frame rail without dropping the tank for install. Titanium Signature Series is the flagship: frame-mounted, with the highest filtration and the widest power band. Titanium Signature Plus adds heavier-duty internals for high-horsepower builds.

What GPH should I get?

Stock trucks up to ~600HP run fine on 100GPH. 600-900HP builds typically want 140-165GPH. 900HP+ and competition trucks need 220-290GPH. When in doubt, size up — pumps don't lose efficiency at part throttle.

Will a fuel system upgrade void my warranty?

Aftermarket fuel system upgrades can affect powertrain warranty coverage on certain components per Magnuson-Moss Act. The dealer must prove the aftermarket part caused the failure to deny coverage. Consult your dealer for specifics.

Ordering

Do you ship internationally?

We can quote international freight on a case-by-case basis. Contact us before ordering.

Do you offer discounts on bulk orders?

Yes — shop or fleet orders may qualify for bulk pricing. Email sales@graysoncountydiesel.com with your list.

Are parts new or remanufactured?

Unless explicitly stated (e.g. "Reman" or "Remanufactured" in the product title), all parts ship new from the manufacturer.

Apparel

Are apparel items pre-shrunk?

Yes — all our shirts and hoodies are printed on ring-spun cotton or cotton-poly blends that have been pre-shrunk.

What sizes do you carry?

Tees and hoodies typically run S through 3XL. Check the size chart on the individual product page.