Don't know it as one piece, but the harness is LVA17501, the 3rd funtion grip half is LVU16650, and the other half of the grip is LVU16701. There are tapping screws and bolts to assemble it as well. Switch and handle halves are common across many tractor models.
Cat D3, Deere 110 TLB, Kubota BX23 and L3800 and RTV900 with restored 1948 Deere M, 1949 Farmall Cub, 1953 Ford Jubliee and 1957 Ford 740 Row Crop, Craftsman Mower, Deere 350C Dozer 50 assorted vehicles from 1905 to 2006
Thanks for starting this thread because it's on my to do list.
The third button is a blank from the factory. Bolton Hooks is developing a kit to add functionality to this blank switch. It is a pricey upgrade, but it you have to replace or add the handle switch; it may be an option.