[Eric B]

Here are the measurements

Formation sign
The Formation Signs were located on the front left windshield and left rear bumperette, 7 inches (17.7 cm) wide x 5 1/2 inches (13.8 cm) tall. Originally painted to an aluminum or metal plate, which was attached by bolts, but by 1944 were being produced as a transfer.
Sometimes these were painted on the rear of a trailer in conjunction with the Unit sign. When painted on the rear bumperettes these were 7 x 5 Inches (12.8 x 17.8 cm)
The formation signs when painted on the windshield outer frame were 2 inches (5.1 cm) from the outside edge and flush with the top edge just bellow the glass.

Unit sign
The Unit signs were initially painted on the reverse side of the pass plate and displayed when pass sign was not in use.
The pass plate bracket was attached to the left front bumper and the rear left side of the body.
The Pass plate sign was 8 ½ inches wide x 9 ½ inches (21.6 x 24.5 cm) tall.
In 1942 the unit sign was located on the front right windshield and right rear bumperette. Originally these were painted on an aluminum or metal plate, which was bolted onto the vehicle, or later directly to the vehicle. By 1944 these background colours were available in transfers. When using these transfers, only the numbers were required to be painted.
Sometimes these were painted on the rear of trailers in conjunction with the Formation sign.
When painted on the rear bumperette the size was 5x7 inches (12.8 x 17.8 cm) as it had less surface to use than the front windshield.
The units signs when painted on the windshield outside frame were 2inches (5.1 cm) from the outside edge and flush with the top edge just bellow the glass.
The Unit number was 5 3/4 inches (15.4cm) tall
Artillery units used a 8 x 8 inch (20.3 x 20.3 cm) square

Thanks Eric