I assume that you are talking about the propane tank on your class C that is slung under the frame of your MOHO? 76 pounds is the maximum capacity that the tank will hold AT the 80% level. Your tanks overall capacity would be 95 pounds X 80% = 76 pounds. The external spit valve on the tank, if used by the filling tech would start spitting fully as soon as the 76 pound level was achieved. Your tank does not likely have an OPD valve so the spit valve should always be used when filling. This is all hoping I got the question understood properly.
Cheers!
Mike