Can the 8K knob be installed on a 9K chassis? March 02, 2016 17:00 Answer No, the two are not compatible. Applies To 9K, 8K Additional Information Related articles What is the Part Number for the 40H Trim Cassettes Lubricant for key combinator? 40H Mortise Spindle Kit Update 9800/F9800 Narrow Stile Surface Verticle Rod Exit Devices How to Order: 45H Visual Indicator Thumb-Turn Kit