Auxiliary Mainshaft

The PAI Industries 900158 Auxiliary Mainshaft is engineered to meet OEM reference Fuller 4300904 for Fuller and Freightliner transmissions. With a 5/8-18 thread and 18 & 10 outer teeth, this mainshaft provides precise gear alignment and durability in auxiliary transmission sections. Manufactured in high-quality, hardened steel for long life under heavy use. Available from Wofford Truck Parts, it delivers reliable performance for transmission maintenance and rebuilds.

Pai Industries Part No: 900158

$254.43

Specifications

The PAI 900158 Auxiliary Mainshaft (OEM Fuller 4300904) is a replacement component designed for use in Fuller auxiliary transmission sections found in various Freightliner, Mack, and other heavy-duty trucks. Key features include a 5/8-18 thread and dual-outer tooth counts (18 & 10) that match the original gear geometry for proper meshing and wear pattern. Constructed from hardened steel, it resists fatigue, wear, and torsional stress. Crafted by PAI Industries, which follows rigorous quality / ISO standards, this mainshaft helps ensure smooth shifting, reduced vibration, and reliable service life. Wofford Truck Parts stocks this part for fleet operators, shops, and operators demanding dependable performance under harsh operating conditions.

Weight

18.64

Compatibility

Freightliner – various models (FLD, Classic, Cascadia, Century, Columbia) — 1980s–2010s.

Mack – CH, CL, CX, and other Mack models that were specified with Fuller transmissions — 1980s–2010s.

Volvo – VN / VNL series and other Volvo tractors equipped with Fuller transmissions — 1990s–2010s.

Kenworth – T600, T800 and other models when fitted with Fuller transmissions — 1980s–2010s.

Peterbilt – 377, 379, 386, 387 and other heavy-duty models with Fuller transmissions — 1980s–2010s.

International/Navistar – 9200/9400/9900 and other line-haul models that used Fuller transmissions — 1990s–2000s.

Various vocational & specialty OEMs (eg. refuse, mixer, heavy-haul chassis) that spec’d Eaton/Fuller transmissions — 1980s–2010s.

Alternative Part Numbers

Fuller 4300904
PAI 900158
Mack 3088-4300904
Freightliner FUL4300904
Other: F6HZ7061CA
S-E322

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Auxiliary Mainshaft - 900158 $254.43