GX20072 42 Inch Deck Belt for John Deere Lawn Mower D105 E100 D110 S100 D100 D120 D125 D130 L100 L110 E110 E120 E130 LA100 LA105 LA110 LA115 LA120 LA125 LA135 S110 S120 GY20570 / 104" Mower Deck Belt

What It Is

This is a 42-inch replacement deck belt for select John Deere lawn tractors with a 42-inch or 104-inch (equivalent) mower deck. It drives the blades via the engine pulley, and is commonly used on the D100, E100, S100, L100 series and many LA models.

Fitment & Compatibility

Before buying, confirm your mower has a 42-inch deck (measure blade tip to blade tip). This belt replaces OEM part numbers GX20072 and GY20570. It fits John Deere models: D100, D105, D110, D120, D125, D130, E100, E110, E120, E130, S100, S110, S120, L100, L110, LA100, LA105, LA110, LA115, LA120, LA125, LA135, and some 104-inch deck variants.
Check your current belt’s part number—if it’s GX20072 or GY20570, this is a direct drop-in. If your mower uses a different belt (e.g., GX20073 for 48-inch decks), this won’t fit. Measure belt length if unsure: the GX20072 is approximately 104 inches long (when laid flat).

Key Things to Know

• Quality: This is an aftermarket belt, not OEM John Deere. For $12, it’s a budget option—expect shorter lifespan than a $30–$40 OEM belt, but adequate for seasonal residential use.
• Installation: Moderate difficulty. You’ll need to release the deck tension (spring or idler pulley), route the belt around all pulleys (check diagram under your deck or in the manual), and re-tension. Allow 20–40 minutes.
• Common gotchas: The belt may be slightly stiff out of the box—flex it by hand before installing. Ensure the belt is seated fully in all pulley grooves to avoid slipping or premature wear. If your old belt broke, inspect pulleys for damage.
• Deck size confusion: Some John Deere 42-inch decks are labeled “104-inch” (the belt’s total length). Double-check your deck model—if it says “42C” or “42-inch,” this belt fits.

Should You Buy It

Buy this if you need a quick, cheap replacement for a 42-inch deck John Deere and are comfortable with a non-OEM belt that may wear faster. It’s ideal for budget-conscious homeowners mowing a standard lawn (1–2 acres). Skip it if you need maximum durability for heavy commercial use or prefer OEM parts for guaranteed fit and longevity.