MowerPartsGroup (2) Blades for John Deere 42" X350 with Accel Deck M170639, UC22008

What It Is

This is a set of two OEM-replacement mulching blades (M170639 / UC22008) for John Deere 42-inch Accel Deep Deck mowers, designed to lift and cut grass more aggressively than standard blades, leaving finer clippings that decompose faster.

Fitment & Compatibility

Check these before buying:

• Deck size: Fits only 42-inch Accel Deep Decks (not standard 42-inch decks). Look for “Accel Deep” or “Accel” on your mower’s deck sticker.
• Model compatibility: Confirmed for John Deere X350, X354, X370, X380, X390, X394, Z335E, Z345R, Z345M, Z355R, Z375R, Z385E, Z395R, and select S240/S250 models with Accel deck. Verify your model’s deck code (e.g., “42A”) on the deck label.
• OEM vs aftermarket: These are aftermarket blades, not John Deere genuine. They match OEM part numbers M170639 (mulching) and UC22008 (bagging) in dimensions and hole pattern, but may differ slightly in steel thickness or coating.
• Measurements: Blade length is 20.5 inches, center hole 1.0625 inches, and two offset mounting holes 3.5 inches apart. Measure your old blade to confirm.

Key Things to Know

• Installation difficulty: Easy. Remove the center bolt (15/16” socket), swap blades, torque to 50-70 ft-lbs. No special tools needed, but a blade removal tool helps if the bolt is seized.
• Mulching vs bagging: These blades have a more aggressive lift for mulching. If you primarily bag grass, the UC22008 version with less lift may be better—this set includes both, so you can choose.
• Sharpness out of box: Blades come sharp but not razor-edge. You may want to sharpen them before first use for best cut quality.
• Balance: Check blade balance after installation. An unbalanced blade can cause vibration and damage the spindle. Use a simple blade balancer or hang on a nail.

Should You Buy It

If you own a John Deere X350 or similar with the Accel Deep 42-inch deck and want a reliable, budget-friendly alternative to OEM blades that still delivers good mulching performance, this set is a solid choice. Skip it if you need genuine John Deere parts for warranty reasons or if your deck is a standard (non-Accel) 42-inch model.