That ^^^^. If it is the air compressor gear drive, a failure while running is almost always fatal to the engine. At the very least, it'll badly dent your wallet. Get the engine serial number, and start doing some research. If it wasn't part of the serial number series affected, problem passed. If it's in the range affected, get ahold of Cummins directly. If it's been repaired at a Cummins shop, it'll be in their records. If it doesn't come up in their system, get a mobile guy to have a look for evidence of it being worked on. Get him to point out everything he's looking at to find evidence of work or none. If you can't find any evidence, it's time to start pricing the repairs. Talk to every Cummins shop in the valley, they can all work on it. Except, maybe TEC. You won't get any fault codes, until the big bang happens. Then you won't need a code to tell you that you've got problems.