John Deere OEM Mower Deck V Belt 42" Deck LT 133 155 160 166 170 180 M128733

What It Is

This is a John Deere OEM M128733 V-belt that drives the mower deck blades on 42-inch cutting decks. It’s designed for select John Deere LT series lawn tractors (models LT133, LT155, LT160, LT166, LT170, LT180) and replaces the original belt when worn or broken.

Fitment & Compatibility

Before buying, confirm your deck is exactly 42 inches (measured blade tip to blade tip). This belt fits only 42-inch decks on the listed LT models—do not use on 38-inch or 48-inch decks. Verify your tractor’s model number (stamped on the frame near the hood or under the seat). This is an OEM John Deere part, so it matches original specs in length, width, and construction. Aftermarket alternatives exist but may vary in durability or fit. Measure your old belt length (end to end, flat) if possible—OEM length is roughly 96.5 inches.

Key Things to Know

• Quality: OEM belt is reinforced and resists stretching better than cheap replacements. Expect longer life under heavy use.
• Installation difficulty: Moderate—requires removing the deck or using a tensioner tool. No special skills needed, but follow the deck diagram (often under the seat or in the manual).
• Common gotcha: The belt routing is specific; wrong routing causes slipping or blade speed loss. Take a photo of the old belt before removal.
• Price note: At ~$52, it’s pricier than generic belts, but often lasts 2–3 seasons vs. 1 season for cheaper options.

Should You Buy It

If you own a 42-inch deck LT133 through LT180 and want reliable, hassle-free operation, this OEM belt is a solid choice. It’s worth the extra cost for durability and exact fit, especially if you mow frequently or have a large lawn. For occasional use on a tight budget, a quality aftermarket belt might suffice, but expect shorter life.