Aluminum Locking Diesel Fuel Cap, 3.00 Inch Diameter (Part Number FC0183-6) by Cleveland Tank. Heavy-duty locking fuel cap machined from lightweight, corrosion-resistant aluminum to resist leaks, cracks, and fuel contamination. Features a 3.00-inch nominal diameter with female threads at 8 threads per inch (8 TPI), a non-vented design, and a built-in locking mechanism to help deter fuel theft and tampering. Weighs 1.0 lb with overall dimensions of 3.0 x 3.0 x 2.0 inches. Designed as a direct-fit replacement diesel fuel tank cap for fuel systems requiring a 3.00-inch female-thread, 8 TPI fitting. Suited for fleet, vocational, and commercial truck fuel tank applications where a secure, weather-tight, anti-corrosion locking fuel cap is needed.

The FC01683 from Cleveland Tank is a 2.00-inch diesel fuel cap sized for smaller fuel system openings than Cleveland Tank’s standard 3- and 4-inch caps. It has a female thread design at 11.25 threads per inch (11.25 TPI) — a finer pitch than the 8 TPI spec used on the larger caps in the line — so getting the thread count right matters for a proper seal. Machined from lightweight, corrosion-resistant aluminum, it resists the rust and pitting that shorten the life of a steel cap. This is a non-locking, non-vented cap, built for diesel fuel systems that don’t require a keyed lock. At 1.0 lb and 2.0 x 2.0 x 2.0 inches, the FC01683 is a direct-fit replacement for diesel fuel tanks specifying a 2.00-inch, 11.25 TPI female-thread cap.