John Deere Mulching Blade Kit for 42 Mowers (Includes 2 Blades and Hardware) - AM140975

What It Is

The John Deere AM140975 Mulching Blade Kit is an OEM set of two mulching blades plus mounting hardware, designed to replace standard blades on 42-inch John Deere mower decks. It’s intended for operators who want finer grass clippings that decompose quickly and don’t require bagging.

Fitment & Compatibility

• Deck size: Only fits 42-inch cutting decks. Measure your deck width to confirm.
• Models: Compatible with John Deere X300, X304, X320, X324, X340, X360, X380, X384, X390, and select LA and D-series (e.g., D100, D105, D110, D120, D125, D130, D140, D150, D155, D160, D170, LA105, LA115, LA125, LA135, LA145, LA155, LA165, LA175). Check your owner’s manual for AM140975 part number reference.
• OEM vs aftermarket: This is a genuine John Deere part, so fit, balance, and heat treatment are guaranteed. Aftermarket blades may be cheaper but can differ in thickness and hole alignment.
• Measurements: Each blade is approximately 21 inches long, 2.5 inches wide, with a 1-inch center hole and 0.5-inch offset. Verify your current blade length and hole pattern before ordering.

Key Things to Know

• Quality: OEM blades are made of hardened steel with a powder-coated finish to resist rust. They hold an edge longer than many aftermarket options.
• Installation difficulty: Moderate. You’ll need a socket wrench, torque wrench, and jack or ramps to access the deck. Torque the blade bolts to 40-50 ft-lbs (check your model’s spec).
• Common gotchas: The kit includes new bolts and washers—always use them. Old hardware can strip or loosen. Mulching blades have a higher lift angle than standard blades, which increases engine load; you may need to mow slower or make two passes in tall grass.
• Deck compatibility: Not for 42-inch decks with a “quick-attach” system or older models like the LX series. Verify your deck model (e.g., 42C, 42M) on John Deere’s site.

Should You Buy It

Buy this kit if you own one of the listed 42-inch John Deere mowers and want OEM reliability with fine mulching performance. It’s ideal for homeowners who mow regularly and prefer leaving clippings on the lawn. Skip it if you bag or side-discharge—standard blades work better for those uses—or if your deck is older than 2005 (check compatibility first).