The Fuller 4303666 is a precision-engineered countershaft gear designed for use in Eaton Fuller heavy-duty manual transmissions. Built to withstand the extreme torque and rotational demands of Class 8 driveline systems, this gear plays a critical role in synchronizing power distribution between the mainshaft and auxiliary sections of the transmission. Manufactured to OE standards, the 4303666 features hardened steel construction for superior wear resistance and longevity under heavy loads and extended service intervals.
Commonly found in select Eaton RT and RTO series transmissions, the 4303666 countershaft gear is essential for maintaining optimal gear mesh, smooth operation, and long-term drivetrain performance. It is a trusted replacement choice for fleet technicians and rebuilders looking to restore OEM-level durability and transmission reliability.
