Work truck I used to drive had a 8.1/Allison combo. For some reason it loved to chew through flywheels. Some would crack, but most would wear the teeth down on the ring gear in a single section. Starter teeth harder than the ring. Our use is a little different though since the start/stop cycle on those would sometimes hit almost 200 times a day. Average day for me was about 130 cycles. I got so used to the sound I would let the mechanic know about a month before it went out. Had a piece of wood in the truck so when it went I could spin the motor with crank pulley and get moving again. The way it was sounding, I'm thinking it will go down sometime in March again.
