(2 Pack) Replacement Lawn Mower Mulching Blades for John Deere GY20850 GX22151 AM137328 AM141033 AM137333, Fits 105 115 125 135 LA100 LA105 LA110 LA115 LA120 for 42" Deck Mower

What It Is

This is a 2-pack of replacement mulching blades designed for 42-inch deck mowers, primarily for John Deere LA-series and 100-series lawn tractors. They replace OEM part numbers GY20850, GX22151, AM137328, AM141033, and AM137333, and are intended for mulching grass clippings into fine particles that decompose quickly.

Fitment & Compatibility

Before buying:

• Deck size: Only for 42-inch (107 cm) cutting decks. Measure your deck width to confirm.
• Models: Fits John Deere 105, 115, 125, 135, LA100, LA105, LA110, LA115, LA120. Also fits some X300-series with 42" decks—check your manual.
• OEM cross-reference: These replace John Deere GY20850, GX22151, AM137328, AM141033, AM137333. Confirm your current blade part number.
• Blade dimensions: Each blade is ~21 inches long, 2.5 inches wide, with a 1-inch center hole and 5-point star drive. Measure your old blade’s length and center hole shape to match.
• Deck compatibility: Not for 48" or 54" decks. Will not fit 100-series with 38" decks.

Key Things to Know

• Quality: Aftermarket steel; some users report slightly thinner metal than OEM, but still durable for residential use. Expect 1-2 seasons of normal mowing.
• Installation difficulty: Easy—remove deck, swap blades, torque bolts to 50-60 ft-lbs. Use a blade removal tool or block of wood to prevent spinning. Wear gloves; blades are sharp.
• Common gotcha: These are mulching blades, not standard lift blades. They produce finer clippings but won’t bag or discharge as well. If you need bagging, buy a different blade type.
• Balance check: After install, verify blade balance to avoid vibration. Use a blade balancer or hang on a nail. Unbalanced blades can damage spindle bearings.

Should You Buy It

If you own a John Deere LA100-series or 100-series tractor with a 42" deck and primarily mulch grass, this 2-pack is a solid budget-friendly alternative to OEM blades. It’s not for heavy-duty commercial use or if you need bagging performance, but for residential lawns, it delivers good mulching results at half the OEM cost.