OEM John Deere GX21784 Blades - Set of 3

What It Is

This is a set of three OEM John Deere GX21784 blades designed for 48-inch and 54-inch mower decks on select John Deere lawn tractors and zero-turn mowers. They’re for medium to large residential yards and light commercial use.

Fitment & Compatibility

• Check deck size: This set fits John Deere 48-inch (e.g., D140, X304, X534) and 54-inch (e.g., X540, X584, Z445, Z645) decks. Confirm your deck model, not just tractor model.
• OEM only: These are genuine John Deere blades. Aftermarket alternatives (e.g., Oregon, Stens) exist but may vary in thickness, shape, or balance. OEM ensures exact fit and warranty compliance.
• Measurements: Each blade is 18.5 inches long, 2.5 inches wide, with a 0.25-inch center hole and a 5-point star center drive. Measure your old blade length and center hole pattern before buying.
• Cross-check part numbers: GX21784 replaces earlier numbers like GX20290, GX20314, and GX20437. Verify your model’s parts list online.

Key Things to Know

• Installation is easy: Remove the old blades with a socket wrench (typically 15/16-inch or 5/8-inch bolt), install new ones with the lift edges facing up toward the deck. Torque to 30-50 ft-lbs.
• Sharpen or replace: These are standard (not mulching or high-lift) blades. Replace when nicked, bent, or after 25-50 hours of mowing. Sharpen if only dull.
• Balance matters: Always balance new blades after sharpening or if they feel off. An unbalanced blade vibrates the deck and can damage the spindle.
• Common gotcha: The star center drive is fragile—don’t overtighten or use an impact wrench at full power. Hand-tighten with a torque wrench.

Should You Buy It

Buy this set if you own a compatible John Deere 48-inch or 54-inch deck and want a guaranteed fit, OEM quality, and no guesswork. It’s ideal for owners who value durability and don’t want to troubleshoot aftermarket alternatives. If you only need one blade or prefer a lower-cost option, look for a single OEM blade or a reputable aftermarket brand.