GX21833 GX20571 Deck Belt Replacement Belt Length 141.7" for John Deere D140 D150 D160 L120 L145 L155 LA130 Z255 Z355 with 48" Decks

What It Is

This is an aftermarket replacement deck belt for select John Deere lawn tractors and zero-turn mowers with 48-inch decks. It measures 141.7 inches in length and replaces OEM part numbers GX21833 and GX20571, transferring power from the engine pulley to the deck spindles.

Fitment & Compatibility

Before buying, confirm your mower model and deck size. This belt fits John Deere D140, D150, D160, L120, L145, L155, LA130, Z255, and Z355 — only those with 48-inch decks. Measure your old belt end-to-end (flat, not twisted) to verify 141.7″ length. It is an aftermarket alternative to OEM John Deere GX21833 and GX20571. Check your deck’s belt routing diagram (usually under the deck or in the manual) to ensure the belt path matches. Not compatible with 42″ or 54″ decks.

Key Things to Know

• Quality: Aftermarket, not OEM. Expect decent performance for the price, but lifespan may be shorter than OEM belts under heavy use.
• Installation: Moderate difficulty. You’ll need to release the deck tensioner pulley and route the belt around all three spindles and the idler pulley. A wrench and a diagram are helpful.
• Common gotcha: The belt must be routed exactly as shown in your model’s diagram — wrong routing causes slipping or rapid wear. Take a photo before removing the old belt.
• Check pulleys: Inspect spindles and idler pulleys for wobble or wear. A bad pulley will destroy a new belt quickly.

Should You Buy It

If you have one of the listed John Deere models with a 48″ deck and want a budget-friendly replacement for a worn or broken belt, this is a solid pick. It’s not for heavy commercial use, but for residential mowing it offers good value. Just confirm your deck size and belt length before ordering.