Back in the 1950's there was a trucking company in Nashville called "Super Service". Their trucks ran over the Smoky mountains into North Carolina, among other routes, long before the Interstate highway system came along. They ran pug-nosed White trucks with inline six gasoline engines of some type- - - -don't remember the make, but I believe they were big Continental engines of some sort. Detroit Diesel sold them on the idea of replacing their gas engines with 2-stroke Diesels, but there was a problem- - - -the 6-71 was too long to fit the engine compartment, so they used 4-71's. OK- - -so far, so good, but the engines had to stay wound up all the time to develop enough HP to pull the mountain grades on the 2-lane highways of the day. New Detroits only lasted 100K miles before they needed an overhaul, and even with a fully equipped in-house machine shop, the best the company could get out of rebuilt engines was around 70K. They kept excellent maintenance records, and every engine had a paper trail of service and overhaul procedures. A tag such as the one in the picture would have been needed for tracking each engine in the fleet.
They also kept DC generators and regulators as matched pairs, and anytime one item was changed they were swapped as a set, and the take-offs were sent to Dad's shop for rebuilding and calibration on his Sun generator tester. They got swapped out on a time and/or mileage basis, and there were very few electrical breakdowns encountered out on the road.
Jerry
