UDC Parts 954-05078 Deck Belt Replacement for Cub Cadet 50 Inch ZT1 50 RZT 490-501-C070 Troy Bilt Mustang 754-05078 490-501-M070 Craftsman Z550 Z5600 Zero-Turn Mowers/Aramid Cord / 143.5 inch

What It Is

This is a 143.5-inch aramid cord replacement deck belt for 50-inch zero-turn mowers. It drives the mower blades on specific Cub Cadet, Troy-Bilt, and Craftsman models, including the ZT1, RZT, Mustang, and Z500/Z600 series.

Fitment & Compatibility

Before buying, verify your mower has a 50-inch deck—not 46 or 54 inches. This belt replaces OEM numbers 954-05078, 754-05078, 490-501-C070, and 490-501-M070. It fits Cub Cadet ZT1 50, RZT 50, Troy-Bilt Mustang 50, and Craftsman Z550/Z5600 zero-turn mowers. Measure your old belt end-to-end: it must be exactly 143.5 inches. Check your deck’s belt routing diagram—some models use a spring-loaded idler pulley that requires proper tensioning. This is an aftermarket belt, not OEM, so confirm your deck’s pulley configuration matches the aramid cord design (standard for most 50-inch decks).

Key Things to Buy

• Aramid cord construction is stronger and longer-lasting than standard rubber belts, but it’s slightly stiffer—expect a tighter fit during installation.
• Installation difficulty is moderate. You’ll need to remove the deck or at least the belt guard, and use a wrench to relieve tension on the idler pulley. A belt installation tool helps.
• Common gotcha: The belt may appear too short because it’s stiffer. Don’t force it—double-check routing and idler position. Some users report needing to loosen the idler bracket bolt for enough slack.
• Wear in period: Aramid belts can squeak for the first few minutes until they seat. This is normal and goes away.

Should You Buy It

If you own one of the listed 50-inch zero-turn mowers and want a durable, budget-friendly alternative to OEM belts, this is a solid choice. The aramid cord offers good longevity for the price, but be prepared for a slightly tighter install than a rubber belt. It’s not for you if you want a drop-in replacement with zero effort—stick with OEM if ease of installation is your priority.