slight - I see all of these as slight because they can be undone, if anyone would ever want to:
prelube, spin on filters, replacing the spare with a generator set, putting on 11.00x20's, adding a drop hitch, fuel up and adding pyro and boost guages, flame heater operation detector, putting the resistor for the heater inside the cab firewall rather than outside in the engine compartment, adding headlamp-size back up lights, adding a battery equalizer and a 12V bus, including an underdash lighter socket, VIC intercom, map lights, additional guage illumination, bumper mounted antennas, and a GPS with a 5" screen using a dash mounted pedestal.
may the purists recoil in horror..