GX20072 Mower Deck Belt (42-Inch) – Fits John Deere D100, D105, D110, D120, D125, D130, LA115, LA120, S100, S110, S120 – Replaces GY20570, UC32283

What It Is

This is a 42-inch mower deck drive belt that transfers power from the engine pulley to the blade spindles on select John Deere lawn tractors. It’s a direct replacement for worn or broken belts on D100, D105, D110, D120, D125, D130, LA115, LA120, S100, S110, and S120 models.

Fitment & Compatibility

Before buying, confirm your deck is exactly 42 inches (measured blade tip to blade tip). This belt fits only 42-inch decks, not 48-inch or 54-inch. Check your model number on the tractor’s frame tag (under the seat or on the hood). This aftermarket belt replaces OEM part numbers GY20570 and UC32283. Measure your old belt’s length (end to end, flat) – it should be roughly 93.5 inches. If yours is longer or shorter, this belt won’t work. Also verify your deck has a single belt (not a dual-belt system) – common on these models.

Key Things to Know

• Quality concerns: Only 1 review with a 3.0 rating suggests average durability. Aftermarket belts often wear faster than OEM (John Deere branded) belts, especially under heavy use or in wet grass.
• Installation difficulty: Moderate – you’ll need to remove the deck or at least the belt guard. A belt routing diagram (usually on the deck or in the manual) is essential. Use a wrench to release the tensioner pulley.
• Common gotcha: If your deck has a spring-loaded idler pulley, ensure the belt sits fully in the pulley grooves before releasing tension. A misrouted belt will slip or throw off blades.
• Check pulley condition: Worn or rough pulleys will shred any belt quickly. Spin each pulley by hand – if rough, replace them before installing the new belt.

Should You Buy It

If you need a quick, cheap fix for a worn belt on a 42-inch John Deere tractor and don’t mind replacing it sooner than an OEM belt, this is a budget-friendly option. But for heavy mowing or if you value longer life, spend a few dollars more on an OEM John Deere belt (part GY20570) – it usually lasts 2-3 seasons versus this one’s likely 1-2.