Thru-Frame Fittings -3an x 1/8in npt Long

The Billet Specialties Thru-Frame Fittings -3AN x 1/8in NPT Long (Part #66310) is a precision hydraulic adapter engineered for applications requiring reliable fluid line routing through frame-mounted bulkheads. This straight-design fitting transitions from 1/8-inch NPT female bulkhead threads to 3 AN male connections, making it ideal for custom hydraulic system installations in high-performance and motorsport applications where space constraints and structural integrity are critical.

Built from stainless steel, this thru-frame adapter resists corrosion and thermal cycling common in engine bays and demanding environments. The 2-3/8-inch length provides adequate clearance for bulkhead mounting while maintaining compact overall dimensions (5.25 x 0.85 x 6.05 inches). Included jam nuts and washers ensure secure, leak-free assembly and allow for straightforward installation without requiring specialized tools. The straight geometry eliminates directional restrictions, simplifying integration into complex plumbing layouts where angled fittings would prove incompatible.

This fitting serves enthusiasts building custom cooling systems, fuel delivery networks, and auxiliary hydraulic circuits on race cars, hot rods, and high-output street vehicles. The NPT-to-AN conversion is particularly valued in systems transitioning between legacy NPT bulkhead fittings and modern AN-standard quick-disconnect or braided hose connections. Sold as a pair, these adapters streamline dual-circuit installations or provide a spare for redundancy-critical applications.

Billet Specialties fittings are recognized in the automotive aftermarket for material quality and dimensional consistency. Stainless construction in thru-frame applications eliminates galvanic corrosion concerns when mixed with aluminum or magnesium frame components—a common failure point in budget alternatives. This adapter represents the engineering-grade standard expected in systems where fluid pressure, temperature cycling, and long-term reliability directly impact vehicle performance and safety.