Freightliner SD 108-122 Fuel Tanks

Frequently Asked Questions About Freightliner SD 108-122 Fuel Tanks

What specific Freightliner models and years are compatible with these 108-122 gallon fuel tanks?

These fuel tanks are designed to fit Freightliner models including the Classic, Classic XL, FLD 112, FLD 120, and FLD 132 from 1990-2007. The 108-gallon tanks typically measure 23" in diameter, while the 122-gallon tanks measure 25" in diameter. Always verify your truck's specific mounting bracket spacing and frame rail configuration before ordering, as some custom applications may require modifications.

Are these fuel tanks made of aluminum or steel, and what gauge material is used?

Most aftermarket replacement tanks for these applications are constructed from either 14-gauge aluminized steel or .080" - .125" aluminum alloy. Aluminum tanks offer superior corrosion resistance and weight savings (approximately 40-50% lighter than steel), while aluminized steel tanks provide excellent durability at a lower price point. Both materials meet DOT specifications and include internal baffles to reduce fuel slosh.

What additional parts or modifications are needed for installation?

Installation typically requires new fuel tank straps, mounting brackets, and rubber isolators if your existing hardware shows wear. You'll also need fuel line fittings (usually 3/8" or 1/2" NPT), a sending unit gasket, and potentially new crossover lines if installing dual tanks. Some installations may require relocating DEF tanks or modifying exhaust brackets on newer emission-controlled trucks. Professional installation usually takes 3-4 hours per tank.

Do these tanks come with sending units and fuel pickups installed?

Most replacement tanks come as bare units without sending units, fuel pickups, or vents installed. These components must be transferred from your old tank or purchased separately. Standard sending unit openings are typically 5-hole SAE pattern. When reusing old sending units, we recommend replacing the gasket and checking the float arm for proper operation to ensure accurate fuel gauge readings.

What's the difference between round and D-shaped tank styles for my application?

Round tanks are the most common style for these Freightliner models and mount directly to the frame rails using standard strap systems. D-shaped (or rectangular) tanks offer increased capacity in the same space by utilizing a flat back design but may require specific mounting brackets. Round tanks typically provide easier installation and parts availability, while D-shaped tanks can add 10-15% more fuel capacity when frame space is limited.