The GMC CCKW

The braces are to strengthen the hood for the installation of the SCM-1 (Mobile Meteorological Station) Support ML-206-B, the wind indicating equipment mast. Take a look at Fred LaPerriere's K-53D at http://www.cckw.org/forum/viewtopic.php ... ere#p21544. Fred's K-53 also has the original eye bolts used for attaching the mast guy lines on the upper outside corners of the front bumper.

Most photos of the K-53 weather station show the mast on the outside rear wall of the van; the hood mount is apparently rather rare.

If you look at the photo of the rear of the K-53 van you will notice the twin hydrogen generator cylinders used for filling the "met" pilot balloons, the kerosine tank (above the left hydrogen cylinder), and kerosine heater (left rear corner of the van).

The SCM-1 manual of March 1945, TM 11-2409, does not show or refer to the three objects on the roof of the van, nor does it mention what looks like a walkway down the center of the van roof.

Just found the Army Motors letter that armydriver was talking about (you have a great memory).
It's in Army Motors #83 page 2 by Frank Von Rosenstiel.

Later,

Further thoughts on the CCKW with the interesting hood: My research indicates the K-53 vans were built on CCKW353 chassis, not -352, so there is a chance the yellow CCKW's cab was transferred to a new chassis.

I've never seen a CCKW K-53 with a winch in any vintage photo and TM 9-2800 does not list a winch version.

Also, the yellow paint scheme may be indicative of air field ground support use, not tactical use. K-53 weather stations were often placed close to the flight line so crews could be briefed just before departing an air field. For incoming flights, the K-53 weathermen would keep the control tower appraised of weather conditions (wind speed, direction, temperature, etc.) near the air field and on the ground.