Lawn Mower Spindle for Cub Cadet XT1 GT54 Troy-Bilt Mustang 54 XP Craftsman T310 Columbia CGT 5426FAB Snapper SZ2454 Lawn Tractors Mandrel Assembly Replacement Part Number 918-06978 618-06978

What It Is

This is a replacement spindle assembly (mandrel) for the cutting deck of select Cub Cadet, Troy-Bilt, Craftsman, Columbia, and Snapper lawn tractors with 54-inch fabricated decks. It drives the blade rotation and houses the bearings; use it when a spindle is seized, wobbling, or noisy.

Fitment & Compatibility

• Deck size: Only for 54-inch fabricated decks (not stamped or 42/46/50-inch decks).
• Models that use this spindle: Cub Cadet XT1 GT54, Troy-Bilt Mustang 54 XP, Craftsman T310, Columbia CGT 5426FAB, Snapper SZ2454, and similar MTD-built tractors with the same deck.
• OEM cross-reference: Replaces OEM part numbers 918-06978 and 618-06978. Aftermarket (not genuine Cub Cadet), but matches dimensions and bolt pattern.
• What to measure: Spindle shaft diameter (must be 5/8”), mounting hole spacing (typically 3.25” center-to-center on a triangular pattern), and overall height (~5.5”). Confirm your deck’s spindle flange matches.
• Check your deck model number (stamped on deck) – if it ends in “054” or “542” it’s likely correct, but verify.

Key Things to Know

• Quality: Acceptable for the price, but bearings are sealed and not serviceable. If you mow heavy grass or bump often, expect 2-3 seasons before replacement.
• Installation difficulty: Moderate – you’ll need a socket set, a breaker bar for stubborn bolts, and possibly a puller if the old spindle is seized. No special tools required beyond that.
• Common gotcha: The spindle housing is cast aluminum – don’t overtighten the mounting bolts (torque to ~30-35 ft-lb) or you can crack it. Also, the blade bolt is reverse-thread on some decks; check before reassembly.
• Comes with: Spindle assembly only – no blade, pulley, or hardware. Reuse your existing pulley and bolts (or buy new if worn).

Should You Buy It

If you own one of the listed 54-inch deck tractors and need a budget-friendly spindle replacement that works out of the box, this is a solid choice. It’s not OEM, but it fits correctly and performs well for the price. Skip it if you want heavy-duty commercial bearings or a full kit with hardware – you’ll need to buy those separately.