Locknut 3/8"-16 Hex Zinc Plated 290-002579

Zinc-Plated Trailer Locknut / Nylock Nut

The Locknut 3/8"-16 Hex Zinc Plated 290-002579 is a replacement locknut used on compatible EZ Loader boat trailer hardware applications. This EZ Loader locknut is commonly used where a 3/8"-16 threaded fastener requires a locking nut to help keep trailer hardware secure.

This part is also commonly referred to as a nylock nut, nylon locknut, or 3/8"-16 hex locknut. It is zinc plated for corrosion resistance in general trailer service.

Common fitment applications may include select jon boat trailers, PWC trailers, and small accessory mounting locations on certain EZ Loader trailer models. Always confirm the hardware size, thread pitch, and mounting location before ordering.

This is a small hardware item, but correct thread size matters. Always confirm the bolt diameter, thread pitch, bracket style, mounting location, and original EZ Loader trailer hardware before ordering.

This is not a complete bracket, U-bolt kit, bunk assembly, roller assembly, or suspension kit. It is one 3/8"-16 zinc-plated hex locknut unless otherwise stated.

Key Features

• EZ Loader replacement trailer locknut
• Part number 290-002579
• 3/8"-16 thread size
• Hex locknut / nylock-style nut
• Zinc-plated steel finish
• Used with compatible trailer brackets, hardware, and fastening points
• Common fitment may include select jon boat trailers, PWC trailers, and small accessory mounting locations
• Useful when replacing worn, missing, rusted, or damaged trailer hardware

Typical EZ Loader Trailer Applications

This 3/8"-16 zinc-plated locknut is used on compatible EZ Loader trailer hardware applications. Some fitment applications may include select jon boat trailers, PWC trailers, small boat trailer hardware locations, and small accessory mounting points on certain EZ Loader trailer models.

It may also be found around bunk brackets, roller brackets, suspension hardware, frame hardware, support brackets, or other mounting points that use matching 3/8"-16 threaded hardware.

Always compare the part number, bolt size, thread pitch, nut style, and hardware location before ordering.

Why This Locknut Matters

Boat trailers operate in wet, vibrating, and road-exposed environments. A proper locknut helps keep compatible hardware secure where a standard nut may loosen more easily. If a nut is missing, damaged, rounded, rusted, or no longer locking correctly, it should be replaced with the correct size and style.

Installation Considerations

• Confirm the bolt is 3/8"-16 before ordering.
• Do not force the nut onto damaged or mismatched threads.
• Inspect the matching bolt, bracket, washer, and mounting area during service.
• Replace severely corroded or stretched hardware as needed.
• Use proper torque practices for the trailer application.
• After service, recheck the hardware after towing or launching if the application requires it.

Fitment Guidance

This is not a universal nut for every trailer bolt. Correct fitment depends on bolt diameter, thread pitch, nut style, hardware location, and the original EZ Loader trailer setup.

• Confirm part number 290-002579 when possible.
• Confirm the thread size is 3/8"-16.
• Compare the old locknut to the new part before ordering.
• Check whether the application requires washers or other hardware.
• Confirm whether the hardware location is on a jon boat trailer, PWC trailer, accessory mount, bracket, frame, or suspension area.
• Send photos if you are unsure about fitment.

Associated / Compatible Parts

These components are commonly inspected or serviced when replacing trailer locknuts and will be linked as available.

Real-World Insight

Small trailer hardware matters. When replacing a locknut, inspect the full fastening point instead of replacing only the missing nut. If the bolt, bracket, washer, or mounting hole is worn or badly corroded, the new locknut may not solve the real issue.

Questions or Need Help Matching Parts?

We’re based in Hardeeville, South Carolina, and help customers across the country match EZ Loader trailer parts correctly.

Call us before ordering if you are unsure. Photos, measurements, trailer information, and VIN details can help us verify fitment faster.

Need help identifying your trailer style or where a part is located? Our legacy trailer reference site at 411Marine may help you find similar EZ Loader trailer examples.

For an overview of our company profile, business background, and code of ethics, visit 411-Trailers.

What to Have Ready When You Call

• Trailer year, make, and model, if known
• Trailer VIN, if available
• Part number from the original hardware, if available
• Bolt diameter and thread pitch
• Photos of the nut, bolt, bracket, accessory mount, and mounting location