FITS MODELS 40 KW AND 50 KW UR 3S 5D5/166 ARMATURE ROTOR ONAN 201-2363 Appears to have a pto style SHAFT that is approximately 1-5/8" DIAMETER with 16 splines UNIT IS ABOUT 28" LONG AND ABOUT 12" IN DIAMETER CRATED, IT WEIGHS 375 POUNDS NEW OLD STOCK UNIT HAS BEEN IN DRY STORAGE FOR YEARS. If you have further information regarding this or another item I have for sale, please feel free to let me know so that I may post it here for buyers who may not have such information. Winner pays CALCUALTED FREIGHT shipping and handling anywhere in USA. Please look at my other items in my STORE and add me to your favorites list. NOS means new old stock. These are items that are still in new and unused condition that have been on the shelf or in storage for a number of years. Most of my items are in the original factory boxes or cases. Some of these boxes show a good bit of wear and tear from storage time and handling. I try to add to my store listings all the time. Please keep in touch. Most items are sold "AS IS" with a "no return policy" unless stated otherwise in the body of the ad. Please know what you are buying and ask questions if you don't. I will answer all emails to the best of my ability. If you are not satisfied with your purchase please contact me immediately. I am not an expert concerning much of what I sell. Please send part numbers when inquiring about certain parts. Sincerely, Mike No returns. Please do your homework. I do not know what it fits. 11-3-21