MTD 631-04463 Mulch Plug Assembly,Black, 1 x 1 x 1 inches

What It Is

The MTD 631-04463 Mulch Plug Assembly is a factory replacement part that blocks the side-discharge chute on select MTD, Cub Cadet, Troy-Bilt, and Yard Machines mower decks, directing grass clippings back under the deck for finer mulching. It’s designed for 42-inch and 46-inch fabricated steel decks with a square chute opening.

Fitment & Compatibility

Before buying, confirm three things:

• Deck size & type: This plug fits 42" and 46" fabricated (not stamped) decks. Measure your chute opening—it must be roughly 1" x 1" square.
• Model series: Works with many MTD-built mowers from the 2000s onward, including Cub Cadet LTX 1040, Troy-Bilt Bronco, and Yard Machines 42" models. Check your owner’s manual or look up your model number on MTD’s site.
• OEM vs aftermarket: This is genuine MTD—no fitment guesswork if your deck matches. Aftermarket plugs may be slightly undersized and rattle.
• Hardware: The plug uses two existing bolts on the chute bracket; you don’t need extra fasteners, but have a 3/8" socket ready.

Key Things to Know

• Installation is easy: Remove the two bolts holding the side-discharge deflector, slide the mulch plug into the chute, reinstall the bolts. Takes 5 minutes.
• Quality note: The plastic is rigid ABS—durable but can crack if overtightened or if the deck vibrates excessively. Hand-tighten bolts.
• Common gotcha: This plug is not for stamped decks (e.g., most 20" push mowers) or for decks with a round chute. If your chute is round or oval, you need a different plug.
• Mulching performance: Works best with a mulching blade kit (sold separately) and dry grass. Wet, thick clippings may clump under the deck.

Should You Buy It

Buy this if you have a compatible MTD-built 42" or 46" fabricated deck and want a cheap, OEM-guaranteed way to convert from side-discharge to mulching. It’s a no-brainer for occasional mulching—just don’t expect perfect results in wet grass or without mulching blades. If your deck is stamped or the chute opening is non-square, skip it.