GY20850 GX22151 Mulching Blades Fits 42" Deck John Deere S110 S120 S130 D105 D110 D130 X105 X145 X300 La115 LA120 LA125 E110 102 105 115 125 Lawn Mower Replaces OEM AM137333 AM137328 UC21583 2 Pack

What It Is

This 2-pack of mulching blades (model GY20850 / GX22151) is designed to fit 42-inch cutting decks on popular John Deere lawn tractors, including S100, X100, D100, LA100, and 100 series. They replace OEM part numbers AM137333, AM137328, and UC21583, and are intended for mulching grass clippings into fine particles that decompose quickly.

Fitment & Compatibility

Crucial checks before buying:

• Deck size must be exactly 42 inches – these blades will not fit 38-inch, 48-inch, or 54-inch decks.
• Fit models – S110, S120, S130, D105, D110, D130, X105, X145, X300, LA115, LA120, LA125, E110, 102, 105, 115, 125.
• OEM reference – replaces AM137333, AM137328, UC21583. Measure your existing blade length, width, and center hole diameter (typically 1-inch center hole, 3.5-inch blade width, 21-inch blade length). Verify your deck spindle pattern matches.
• Aftermarket note – not OEM, but listed as a direct replacement. If your machine uses a different blade offset or thickness, these may not work.

Key Things to Know

• Quality – 4.9/5 rating from 10 reviews suggests good build and balance, but limited sample size. Expect hardened steel with a coated finish.
• Installation – moderate difficulty. Requires jacking up the mower, removing the old blade bolt (often stuck), and reinstalling with proper torque (typically 70-90 ft-lbs). Use a blade removal tool or block of wood.
• Common gotchas – blades may need sharpening out of the box (check before mounting). Ensure the blade orientation (air lift side up) matches your deck. Over-tightening can warp the blade or strip the spindle.
• Performance – designed for mulching, not bagging or side-discharge. If you often bag clippings, consider a high-lift blade instead.

Should You Buy It

Buy this if you own a 42-inch John Deere lawn tractor from the listed series, need a cost-effective mulching blade replacement (under $40 for two), and the 4.9-star rating gives you confidence. Skip it if your deck size is different, you need OEM parts for warranty reasons, or you primarily bag clippings.