IMPCO STYLE AT2-4-2 T2 THROTTLE BODY CA225 225 200 MIXER NEW OLD STOCK ONAN THROTTLE BODY ONAN 145-0538 the mounting bolt holes for this 145-0538 are 2-15/16" on centers. and the diameter of the center throat with the butterfly valve is 1-11/16". the square plate side of this is 2-7/8" x 2-7/8" 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 $9.95 shipping and handling anywhere in USA. Other countries must contact me for a postage quote. 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 ... ** ask me for help to search 1000's of old, obsolete and discontinued Onan part numbers. Don't forget to click on SEE ALL CATEGORIES in the left hand navigation bar. Powered by Turbo Lister The free listing tool. List your items fast and easy and manage your active items. 11-3-21