National 380003A Wheel Seal for Medium & Heavy-Duty Trucks — PTFE Triple-Barrier, High-Temp Durability

National 380003A Wheel Seal is a heavy-duty wheel end sealing solution built from a proprietary PTFE compound and a triple-barrier design to protect commercial truck wheel hubs from contaminants and high temperatures.

Designed by National, a trusted name in sealing technology for over 75 years, the 380003A is engineered for demanding fleet and vocational applications. It replaces wheel end seals on a range of medium- and heavy-duty trucks, delivering low friction, extended temperature tolerance and robust exclusion of dirt and moisture. The construction and materials focus on durability under mixed-lubricant conditions and repeated wheel movement.

What vehicles does this seal fit?

The National 380003A is made for a variety of Isuzu, Chevrolet and GMC medium- and heavy-duty models across late-1990s to late-2000s model years. Verify fitment by entering your vehicle details before purchase to confirm compatibility and review any fitment notes shown in the product listing.

• Compatible with Isuzu FTR (1995–2011), FVR (1995–2004), HTR (2005–2007), HVR (2005–2008)
• Fits Chevrolet Kodiak/T-series models C6500, C7500, T6500, T7500 across 1997–2009 ranges
• Also fits GMC C6500 Topkick (2003–2009)
• Always check make, model, year, engine and trim in the fitment tool before ordering

How does the seal keep contaminants out during wheel-end movement?

This seal uses a patented lay-down, bi-directional sealing lip that increases contact area as the wheel end moves, improving debris exclusion during rotation and suspension travel. A triple-barrier construction adds redundant protection so dirt and water encounter multiple defense layers before reaching bearings or hub components.

• Patented bi-directional lip increases sealing surface under dynamic conditions
• Triple barrier system provides staged contamination defense
• Designed for repeated start/stop and side-load wheel movement scenarios

What materials and temperature range does the 380003A support?

The seal uses a proprietary PTFE compound chosen for very low friction and broad lubricant compatibility, which is useful where mixed lubricants may be present. It is rated for extreme environments, operating across a wide temperature band so it performs in cold storage or high-heat duty cycles without rapid degradation.

• Proprietary PTFE compound for minimal friction and long wear life
• Compatible with a range of gear and wheel-end lubricants
• Temperature rating: -100°F to 450°F (-73°C to 232°C)

Why choose National Gold 38 Series for wheel-end service life?

The Gold 38 Series applies advanced manufacturing and materials to reduce seal failure modes common in heavy-use vehicles. By combining the PTFE compound with the triple barrier architecture and the specialized lip geometry, the design extends functional life and reduces maintenance frequency compared with generic seals.

• Gold 38 Series technology targets longer service intervals
• Lowest friction profile reduces heat and wear at the contact surface
• Engineered for fleets and vocational vehicles with higher duty cycles

Who is this for: The National 380003A Wheel Seal is intended for fleet managers, truck technicians and DIY mechanics servicing medium- and heavy-duty Isuzu, Chevrolet and GMC wheel ends who need a durable, low-friction seal that works with mixed lubricants and extreme temperatures. If you require a robust replacement seal to minimize downtime and protect bearings from contamination in demanding operating conditions, this part is well suited.