1950 was the first year for the "Big Cab" GMC Heavy Duty Trucks. That's a '55-'59 GMC "Cannonball" COE, that you have here. The '50 -'54's had the Bumper Bar Grille (not the flat grille like yours), & the back of the cabs, were more rounded, & not flat like yours. Nice truck. Here's a link to the 1950 GMC "Cannonball" I owned. Note the Bumper Bar Grille,
http://www.classiccoe.com/friends/spanky/1950_spanky_1b.jpg
