2 PCS Mulching Blades Replacement Fits for John Deere 42" Mower Z TRAK Mower Z335E Z335M Z345M Z345R X330 X350 X354 X370 X380#M170642 UC22008 M170639 GY20683

What It Is

This is a set of two aftermarket mulching blades designed for John Deere 42-inch mower decks. They replace OEM part numbers M170642, UC22008, M170639, and GY20683, and are intended for use on Z-Trak zero-turn mowers and select X300 series lawn tractors. Mulching blades feature a curved, angled design that recirculates clippings for finer cutting and natural lawn fertilization.

Fitment & Compatibility

Before buying, confirm your mower has a 42-inch deck (measured cutting width). These blades fit specific John Deere models: Z335E, Z335M, Z345M, Z345R, X330, X350, X354, X370, and X380. They will not fit 48-inch or 54-inch decks. Measure your existing blade length (should be ~21 inches) and center hole size (typically 1-inch round or 5-point star). Check that your spindle assembly uses a standard center hole—some newer Deere decks use a different pattern. Aftermarket blades are not OEM, so verify the blade thickness (usually 0.25 inches) matches your spindle clearance.

Key Things to Know

• Mulching vs. standard blades: These produce finer clippings and work best with a mulching plug or kit; they can reduce bagging performance.
• Installation difficulty: Moderate. You’ll need a socket wrench and a blade removal tool (or block of wood) to prevent spindle rotation. Tighten bolts to 40-50 ft-lbs.
• Common gotchas: Some users report needing to rebalance blades after purchase. Always check for wobble before first use. Also, these may not fit decks with a different blade offset (e.g., low-lift vs. high-lift designs).
• Durability: Typically made of heat-treated carbon steel; expect similar lifespan to OEM blades with regular sharpening.

Should You Buy It

If you own a compatible John Deere 42-inch mower and want a cost-effective alternative to OEM blades for mulching, this set is a solid choice. It’s ideal for homeowners who mow frequently and prefer fine clippings for lawn health. However, if you prioritize bagging or have a non-standard spindle pattern, stick with OEM or measure carefully first.