Cab Removal?

[FB85C10]

Im getting ready to remove the cab off my 85 c10 and i started on the passenger side under the firewall area i put my wrench on and my breaker bar on it i slowly attempted to turn the bolt it started to come loose then i heard a snap and then the bolt just started to spin along with the top and bottom bushings along with it, is there a nut welded on the inside of the support for the bolt to bolt into cause i think that the welds broke loose and now it spins and i cant see in the support to see if there is a nut or not. So my questions is there a nut inside the support and how do i fix it and get the bolt out, any suggestions? what is the best way to get these cab bolts out any tricks on doing it or no? Help. Thanks!