Inspecting trucks with DDDL or Cummins InSite

Not as familiar with DDDL but with insite I would:
Check the abuse history for low oil pressure/high coolant temp runtime
Check the fault codes
Check the regen history, time vs differential pressure
Check the trip for totals (mileage, hours, ect) and for excessive idling
Preform a cylinder cutout test
Preform a Regen and datalog it
Road test the truck with a bottle on it to check pressurizing
Pull an intake pipe to check for dusting

Plus the standard oil leak inspection, truck inspection, general look over.
If you are not too familiar with the truck/engine it pays to have a good shop take a look at it/ preform a safety to give an assessment of the truck.