Parts Camp 3-Pack 918-04125C Spindle Assembly with Pulley, Replaces MTD Cub Cadet Troy-Bilt Craftsman 918-04125B 918-04126A 618-04126, Fits 50" 54" Deck RZT Zero Turn Mowers & Riding Tractors

What It Is

This is a replacement spindle assembly with a pre-mounted pulley, designed to drive the mower blades on select 50” and 54” deck zero-turn mowers and riding tractors from Cub Cadet, MTD, Troy-Bilt, and Craftsman. It’s a direct aftermarket replacement for OEM part numbers 918-04125B, 918-04125C, 918-04126A, and 618-04126.

Fitment & Compatibility

• Deck size: Fits 50” and 54” fabricated decks only—do not use on stamped steel or smaller decks.
• Brands: Cub Cadet RZT series, MTD, Troy-Bilt, and Craftsman models that use the OEM part numbers listed above.
• Measurements: Confirm spindle shaft diameter (typically 1” or 7/8”) and bolt pattern (3-bolt triangular) match your deck. Measure center-to-center bolt spacing (approx. 3.5”–4”).
• Pulley: Includes a 4.5” OD pulley. Verify your belt width and pulley groove depth match your existing setup.
• Check deck model number (e.g., 50A, 54A) against the manufacturer’s parts diagram—do not rely solely on mower model number.

Key Things to Know

• Quality: Uses sealed bearings and a steel housing. Most users report it’s comparable to OEM, but a few note slightly looser tolerances on the pulley hub.
• Installation: Moderate difficulty—requires removing the deck, belt, and blade. You’ll need a socket set, torque wrench (blade nut ~70–90 ft-lbs), and penetrating oil for rusted bolts.
• Gotcha: The pre-installed pulley may not align perfectly with your deck’s belt path on some models—check belt tension before tightening fully.
• Pack: You get three assemblies (one per spindle), which is cost-effective if replacing all spindles at once, but verify all three are identical (they are).

Should You Buy It

If you have a 50” or 54” fabricated deck on a Cub Cadet RZT or compatible MTD/Craftsman zero-turn and need a budget-friendly all-in-one spindle and pulley replacement, this 3-pack is a solid choice. It’s best for DIYers comfortable with moderate mechanical work and who want to avoid sourcing separate pulleys. Skip it if you need a single spindle or have a stamped steel deck.