The mack 12 speed is a great transmission if you can shift it , its not for the laidback driver ,I've had a couple and no trouble. You do have to make sure the air pressure is ajusted to the right pressure, that makes them shift the best.

a 12 speed mack tranny is a work horse,when its used correctly it can be a very enjoyable relationshiip,but if i were doing the super short stuff,id just find me an 5 spd

bbelay my last,if the 12 speed dies then id put a 5 in,or the 2 stick 5 spd

Mack12 speed was the transmission of choice for Super B trains in the Canadian Rockies for many years, it will be a good transmission for your job.I takes a bit of getting used to but they were well built and I'd go with one every time. Ted Campbell