Iowa Customs 8″ Billet Aluminum Seat Base Adapter – Fits Peterbilt 379, 386 & 389 (National & Knoedler Seats)
Raise Your Ride – Built for Comfort and Precision
The Iowa Customs 8-Inch Seat Base Adapter (IC199001-11) is machined from solid billet aluminum to provide a strong, lightweight solution for adjusting seat height in your Peterbilt. This adapter raises your seat 8 inches to improve driving visibility and ergonomics while maintaining full air-ride suspension function. It’s designed for a perfect fit with National and Knoedler seating systems found in Peterbilt 379, 386 and 389 models.
Product Features
• CNC-machined from premium billet aluminum for maximum strength and precision
• Raises seat base by 8″ for improved comfort and visibility
• Direct bolt-on fit – no cutting, drilling or welding required
• Compatible with National and Knoedler air-ride seat bases
• Includes all stainless-steel mounting hardware for installation
• Polished aluminum finish for show-quality look and corrosion resistance
• Proudly made in the USA
Fitment
• Peterbilt 379 / 386 / 389
• Designed for National and Knoedler seat models with factory mounting pattern
Why Drivers Choose Iowa Customs
• Improves driver comfort and ergonomics on long hauls
• Durable, lightweight billet aluminum construction
• Polished finish matches OEM and custom interiors
• American-made quality and precision machining
Common Questions
Q: Does this come with hardware?
A: Yes — all required stainless-steel mounting hardware is included.
Q: Will this change seat air-ride travel?
A: No — it maintains full range of motion and suspension travel.
Q: Can this fit Legacy or Sears seats?
A: No, this adapter is built specifically for National and Knoedler models.
California Proposition 65
⚠️ WARNING: This product can expose you to chemicals including nickel and aluminum oxide, known to the State of California to cause cancer or reproductive harm. For more information, visit www.P65Warnings.ca.gov.