Any person driving under a commercial class A license shall not be required to obtain a hazardous materials endorsement pursuant to 49 C.F.R. § 383 if the person is:
(a) Acting within the scope of the license holder's employment as an employee of a custom harvester operation; and
(b) is operating a service vehicle that is: (1) Transporting diesel in a quantity of 3,785 liters, 1,000 gallons or less; and (2) clearly marked with a "flammable" or "combustible" placard, as appropriate.