I found this post in the archives and the exact same thing happened to me. It was a Crane toilet and ballcock assembly. I had it for about a year and the ballcock split
My ballcock split on the shank too. It happened on the 15th floor of a highrise. Do you know of any special requirements for ballcocks in high rises? The insurance company is getting very curious. Or do you know what could have caused this? If so, please respond and email me. Thanks.
"I had a fluidmaster ballcock split on the shank where it is threaded for the supply tube nut. The toilet was installed two yrs ago.It made a mess and ruined a beautiful oak wood floor in a log cabin It was factory installed in an eljer toilet, Has any other plumbers ran accross this problem? The fluid master website is down. "