According to this: TB746-93-1 Colour and Marking of Military Vehicles Section 4 Special Markings
14 - Weight Classification.
a) All single vehicles with a gross weight of over 3 tons, and alltrailers with a rated payload exceeding 11/2 tons, are classified for the purpose ofbridge crossing, per FM 5-36. Each single vehicle and vehicle combination has aclassification number for empty, cross-country loading, and highway loading. Theclassification numbers are used to determine whether a bridge, correspondingly classified,can be safely crossed.
b) All applicable self-propelled vehicles not towing other vehicleswill carry a circular sign of 9 inch diameter with the vehicle’s classification number inblack on a yellow background. This will normally be located on the front of the vehicletoward the vehicle’s right side and below the driver’s line of vision.
c) All applicable self-propelled vehicles towing other vehicles willcarry a sign similar in size, design, and location except that the classification numberof the vehicle combination will be shown with the letter C in red above the number. A 6inch yellow circle with the basic vehicle classification number in black will be marked onthe right side of the vehicle in a conspicuous location. The towed vehicle will besimilarly marked with its basic classification number.
d) When the classification number of the vehicle is not subject tochange, the marking may be applied directly on a suitable surface. On vehicles painted ingloss colours, the markings will be gloss yellow, Colour Chip No. 13538; gloss black,Colour Chip No. 17038; and gloss red, Colour Chip No. 11136. On vehicles painted insemi-gloss or lusterless colours, the markings will be lusterless yellow, Colour Chip No.33538; gloss black, Colour Chip No. 17038 and gloss red, Colour Chip No. 11136. When themarking is applied directly to vehicles painted in the same or similar colour, thecircumference of the circle will be outlined with a black circle .3/4, inch wide.
e) In usage’s where the classification number may change, a sign kitwill be utilised which consists of a 9 inch metal disk, a retaining plate, and two sets offive different numeral plates. By installing the retaining plate, the numeral plates willbe locked in place. The sign has black numerals on a yellow background and a red C on oneside of the retaining plate (figure 14).Yep