918-06980 618-06980 Spindle Assembly Fits 50 inch Deck Cub Cadet ZT1 50 RZT L 50 L50 S50 XT1 GT 50 GT50 Troy Bilt Mustang XP 50 Craftsman Z550 G8200 Zero Turn Mower Parts

What It Is

This spindle assembly (OEM 918-06980 / 618-06980) is the rotating hub that drives the mower blade on 50-inch deck zero-turn mowers. It’s a direct replacement for worn or noisy spindles on Cub Cadet ZT1 50, RZT L 50, L50, S50, XT1 GT 50, GT50, Troy-Bilt Mustang XP 50, and Craftsman Z550/G8200 models.

Fitment & Compatibility

• Deck size must be exactly 50 inches – this spindle does not fit 42", 46", or 54" decks.
• Check your model number – fits Cub Cadet ZT1 50 (all variants), RZT L 50, L50, S50, XT1 GT 50, GT50, plus Troy-Bilt Mustang XP 50, and Craftsman Z550/G8200. Not for older RZT 50 (non-L) or non-50-inch decks.
• OEM vs aftermarket – this is an aftermarket replacement, not a genuine Cub Cadet part. It matches OEM dimensions but may use slightly different bearing quality.
• Measure before buying – confirm spindle shaft diameter (typically 5/8"), housing bolt pattern (usually 4-bolt, 3-inch center), and overall height (~4.5"). Compare to your old spindle.

Key Things to Know

• Quality – Decent budget option; bearings are sealed but may not last as long as OEM ($45–60). Expect 2–3 seasons with normal use.
• Installation – Moderate difficulty. Requires removing blade, pulley, and housing bolts. Use a puller if rusted. Torque blade bolt to 50–70 ft-lbs.
• Common gotcha – The spindle may come without grease. Add a small amount of lithium grease to the top bearing before install. Also, check pulley alignment – some aftermarket spindles have slightly different pulley seat height.
• Compatibility note – Will not fit Cub Cadet XT2 or XT3 models, even with 50" decks.

Should You Buy It

Buy this if you need a quick, affordable replacement for a worn spindle on a 50-inch Cub Cadet, Troy-Bilt, or Craftsman zero-turn and don’t want to spend OEM prices. Avoid if you need maximum longevity (go OEM) or if your deck is not exactly 50 inches.