GX20072 Deck Belt Replaces John Deere 42 inch Deck Belt GY20570, Fits John Deere L 100 130 1742 D 100 110 120 130 X 110 125 145 LA 105 Lawn Mowers (1/2" x 104")

What It Is

This is a replacement deck belt for 42-inch cutting decks on select John Deere lawn tractors. It drives the mower blades from the engine pulley, and is designed for residential mowing use.

Fitment & Compatibility

Before buying, verify these three things:

• Deck size: This belt fits only 42-inch decks. Measure your deck or check the model number.
• Model fit: Confirmed for John Deere L100, L130, L1742, D100, D110, D120, D130, X110, X125, X145, and LA105. Does not fit X300 series or larger tractors.
• OEM cross-reference: Replaces John Deere part GY20570. The belt measures 1/2 inch wide by 104 inches long. Measure your old belt’s length (lay it flat) to confirm.
• Aftermarket note: This is a non-OEM belt. It may run slightly tighter or looser than a genuine John Deere belt. Check deck pulley alignment if you have vibration issues.

Key Things to Know

• Quality: Rated 4.5/5 from 161 reviews. Users report it lasts one to two seasons under normal residential use. Not for commercial/zero-turn mowers.
• Installation: Moderate difficulty. You’ll need to remove the deck, route the belt around pulleys and idlers, and re-tension. Watch a video for your specific model—routing errors cause slippage.
• Common gotcha: The belt may be slightly shorter than OEM spec. If your deck uses a spring-loaded idler, this is fine. If it’s a fixed idler, you might need to adjust the tensioner.
• Warranty: Check the seller’s return policy. Some aftermarket belts fail early if stored in extreme heat or cold.

Should You Buy It

If you have a compatible John Deere 42-inch deck model listed above, this belt is a solid, cost-effective replacement for residential mowing. It’s not built for heavy commercial use, but for a few acres of weekly cutting, it delivers good value. Avoid if you need exact OEM fitment or run a zero-turn mower.