Junior may have mentioned a D5. I sort of do remember one of the boys mentioning a CAT D10 and knowing how to get it started, etc. It was part of experiencing first-hand all components and phases of a construction project. Obtaining street cred.
I remember him talking about a Cat, but not which model. As you correctly recall, he was talking about getting to know the details of the job.
Iirc it was in Nevada in a mining community. ,Jr Speaking about 2nd amendments and dropped the D5 comment. (Dad would send the boys over to their grandfathers to work summers because the unions wouldn’t let them really work here. They got lots of work experience there)