2pcs 42 inch Lawn Mower Mulching Blades Fit for John Deere Garden Mowers with 42" Deck Replace OEM GX22151, GY20850, 50-3231

What It Is

This is a pair of 42-inch mulching blades designed for John Deere lawn tractors with a 42-inch cutting deck. They replace OEM part numbers GX22151, GY20850, and 50-3231, and are intended to chop grass clippings into fine pieces for nutrient recycling, reducing bagging needs.

Fitment & Compatibility

Before buying, confirm your John Deere has a genuine 42-inch deck (measure from blade tip to blade tip across the deck). These blades fit most John Deere 100-, 300-, and X300-series tractors with 42" decks, including models like D100, D110, D120, D125, D130, D140, D150, D155, D160, D170, X300, X304, X310, X320, X324, X330, X340, X350, X360, X370, X380, X390, and LA series. Check your current blade’s center hole diameter (typically 1-inch or 7/8-inch) and overall length—these are 21 inches each (two per set). Verify your spindle bolt pattern matches (usually a 5-point star or 5/8-inch center hole). If your deck is 48" or 54", these won’t work.

Key Things to Buy

• Quality: Aftermarket blades at this price point may be slightly thinner or less balanced than OEM. Inspect for burrs or uneven edges before installation; sharpness is decent but not premium.
• Installation: Moderate difficulty. You’ll need a socket wrench, torque wrench (set to 70-90 ft-lbs), and a block of wood to prevent blade rotation. Always disconnect the spark plug first.
• Gotcha: Mulching blades have a curved or “winged” design—ensure they’re installed with the cutting edge facing the direction of rotation (usually upward on the left side). Reversing them reduces performance and can damage the deck.
• Lift: These blades have less lift than standard blades, so they work best in dry, short grass. Avoid heavy, wet clumps to prevent clogging.

Should You Buy It

Buy this set if you own a compatible 42-inch John Deere, want a budget-friendly mulching upgrade, and are comfortable with basic DIY maintenance. It’s a solid value for light-to-moderate use, but if you need maximum durability or have a larger deck, stick with OEM or a premium aftermarket brand.