Replacement: The M158756 extension spring is compatible with John Deere riding lawn mowers, compact tractors, and snow‑blower accessory. Replaces M157886 spring in mower‑deck and PTO drive‑belt tension systems Compatibility: Compatible with John Deere Select X300 series lawn mowers(X300, X300R, X304, X305R, X310, X320, X324, X330, X350, X350R, X354, X360, X370, X380, X384, X390, X394); X500 Series Multi‑Terrain tractors (X500, X520, X530, X570, X580, X584, X590 ); Z425, Z445, Z465 EZtrak zero‑turn mowers; and 1023E, 1025R, 1026R compact utility tractors Fits Mower Decks & Snow Blowers: The M158756 deck‑drive belt tension spring fits 44‑inch mower decks and 47‑inch snow‑blower attachments, and is also found on certain 48‑inch and 54‑inch mower deck systems Material & Specifications: This m158756 lawn mower spring made of high‑tensile steel wire; wire diameter 3.6 mm (0.138 in), OD 26 mm (1.02 in), free length 180 mm (7.09 in), coil length 99 mm (3.9 in), 28 active coils in total Easy Installation: For replacing worn or stretched tension springs. Please confirm compatibility by checking your mower model and verifying the spring’s specifications before purchasing The M158756 extension spring helps maintain proper tension in mower deck and PTO drive belts. Compatible with John Deere X300, X500, Z400 series lawn tractors and 1 Series compact utility tractors. Made of high-tensile steel, this spring features a 3.6 mm wire diameter, 180 mm free length, and 28 coils. Fits 44" mower decks, 47" snow blower systems, and select 48"/54" deck