Mudder Gx20072 42 Inches Mower Deck Belt 1/2 Inch x 104 Inch Compatible with John Deere Mower Deck Drive Belt La100 La105 La110 La120 La125 La135 Replaces Gy20570 M112230 M137547 M86248

What It Is

This is a 42-inch mower deck drive belt (1/2 inch wide, 104 inches long) designed for select John Deere lawn tractors. It transfers power from the engine pulley to the deck spindles, enabling blade rotation for cutting grass.

Fitment & Compatibility

Before buying, confirm your mower has a 42-inch deck (measured blade tip to blade tip). The belt fits John Deere 100-series models: LA100, LA105, LA110, LA120, LA125, LA135. It replaces OEM parts GY20570, M112230, M137547, and M86248. Measure your existing belt length (end-to-end, flat) to verify it’s 104 inches. Check your deck’s belt routing diagram—this belt uses a standard serpentine path around two spindle pulleys and one idler pulley. It does not fit 48-inch decks or non-Deere models.

Key Things to Know

• Quality vs OEM: Mudder is a budget aftermarket brand. Expect shorter lifespan than OEM John Deere belts (GY20570) under heavy use or debris. Good for light residential mowing.
• Installation: Simple for DIYers—remove deck, release tensioner, route belt per diagram, re-tension. No special tools needed, but a belt tool helps.
• Common gotcha: The 1/2-inch width is standard, but some aftermarket belts may be slightly narrower, causing slippage. Check tension after first 30 minutes of use.
• Return policy: At this price point, returns are often not worth it—verify fitment before buying.

Should You Buy It

Buy this if you need a cheap, quick replacement for a 42-inch John Deere 100-series deck belt and you mow a small lawn occasionally. Skip it if you mow heavy, wet, or tall grass regularly—spend more on an OEM belt for durability.