42" Mower Deck Mulch Cover GY00115 Compatible with John Deere 100 LA100 L100 Series S100 S110 S120 S130 S240 X105 X106 X110 X120

What It Is

This is an aftermarket mulch cover kit (part GY00115) designed to replace the factory cover on 42-inch John Deere mower decks. It converts side-discharge or bagging decks into a mulching setup, chopping clippings finer and recirculating them into the lawn.

Fitment & Compatibility

Check deck size first: This fits only 42-inch decks. Measure your deck’s cutting width (blade tip to blade tip) to confirm, not the deck shell.

Model compatibility: Listed for John Deere 100, LA100, L100, S100, S110, S120, S130, S240, X105, X106, X110, X120 series. Some later S-series (S140+) use a different deck. Verify your deck model number (stamped on top of deck) – common compatible decks include 42A, 42C, 42D, 42E, 42F, 42M, 42R, 42S.

OEM vs aftermarket: This is a non-OEM part. OEM part number is GY00115. Fitment should match, but aftermarket covers may have slightly thinner plastic or looser latch fit. Check the mounting holes and latch location match your deck’s existing slots.

What to measure: Deck mounting slot width (~1/4 inch) and latch pin position. If your deck has a different latch style (e.g., spring-loaded vs. twist-lock), this cover may not secure properly.

Key Things to Know

• Installation difficulty: Easy – remove two wing nuts or pins, slide off old cover, slide on new one, and secure with supplied hardware. Usually under 10 minutes.
• Quality notes: Aftermarket covers are often made of ABS plastic. Some users report warping in direct sunlight or cracking after a few seasons. OEM covers are thicker but cost 2-3x more.
• Common gotcha: The cover must sit flush against the deck shell. If it gaps, clippings will blow out and mulching performance drops. Check that the rubber seal (if included) contacts the deck edge.
• Not a universal fix: This only works if you already have a discharge chute opening. It won’t convert a dedicated bagging-only deck.

Should You Buy It

If you have a compatible 42-inch John Deere deck and want to mulch without buying a separate mulching deck or blade kit, this is a budget-friendly solution. It’s fine for occasional mulching on smaller lawns, but if you mow frequently or have thick grass, the thinner plastic may not hold up as long as an OEM cover. Skip it if you need a heavy-duty, all-season part.