Lamont

Bad tyranny mount causes motor to shift belt breaks instantly

My 2014 mack chu613 mp8 motor has went thru 4 a/c - alternator belts in 4 days, replaced tensioner replaced fan hub a/c works fine so does alternator, no problem running up an down highway, but when the truck goes into the landfill, that's usually were the belts break not sure if it could be transmission related mack shop said it was giving out a fault code for 3rd gear an reverse. Any ideas?