Upper and lower guide plate assembly set designed for 400 ATV engines, compatible with JS400 and JS183FMQ models. This set includes parts numbered F3-150000-0 and F3-140000-0, intended for use in engine maintenance and repair. The guide plates are engineered to support proper chain alignment and tension within the engine system. Constructed for durability and consistent performance, the assembly set serves as a functional replacement component for applicable ATV engine models. Compatibility Disclaimer: This is an aftermarket replacement part. Any brand names or model designations mentioned are used solely for the purpose of demonstrating compatibility.