MACK MRU 613 2012 MP7 ENGINE

I SEEM TO BE HAVING A HUGE SETBACK . WE ARE CURRENTLY WORKING ON WHAT WE THOUGHT TO BELIEVE WAS A REAR MAIN SEAL LEAK. WE REMOVED THE TRANSMISSION AND TOOK OUT THE SEAL AND REPLACED IT. P[LEASE NOTE THAT WE ALSO 'PURCHASED THE TOOL NEEDED FOR THE JOB IN WHICH IT INSTALLS THE SEAL SO IT SITS CORRECTLY BECAUSE MACK APPERENTLY CHANGED THE WAY THIER SEAL IS DESIGNED WHICH IN TURN FORCES YOU TO BUY AN EXPENSIVE TOOL FOR IT. LIKE LLIKE TO MENTION AS WELL THAT WE ALSO CHANGE THE CAM BEARINGS AS WELL. UPON DRIVER TAKING IT OUT ON ROUTE IT STARTED LEAKING AGAIN BUT EVEN MORE SO THAN PREVIOUSLY. Any insite on this issue would be greatly appreciated because we are of course forced to have to take the tranny out and reinspect it again.