Husqvarna 539105543 Lawn Tractor Caster Wheel Spacer Genuine Original Equipment Manufacturer (OEM) Part This part is compatible with models including; Z4219BF-968999763,917277840,ZTHQL4221A (968999172),968999656,968999655,917277800,968999219,RZ4619,ZTHKH4820A (968999158),966612301,RZ4219/250201,917204140,917289821,917289820,RZ4219,Z4824BF-968999517,968999172,968999170,965882301,965882101,965880401,RZ5422,CZ4815KAA,CZ3815,917277730,966659301,968999508,Z4619BF-968999764,968999220,966042901,968999301,ZTHKW4821A (968999169),CZ4817KOA,Z4220BF-968999685,917289880,RZ4219BF-966582201,966582201,965881201 This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including; 5391055-43,584653101 Genuine Original Equipment Manufacturer (OEM) part. Compatible Brands: Husqvarna,Craftsman,Dixon,Poulan This caster wheel spacer (part number 539105543) is for lawn tractors Wear work gloves to protect your hands when installing this part