Front-End Loader Need help identifying an FEL nut

[sjthomaslv]

Can anyone tell what these nuts are called, and maybe where to find one? It appears to be a 3/4"-10 holding on the FEL arm. It's a Bush Hog loader on a Kubota L3400. I'm no rocket scientist, but I'd guess it's a pretty important nut. ;-)

Thanks!