Hy Toyvo, in Canada all the 1/2 ton trucks Chev. and GMC from 1948 through 1955"A" have a 116" wheelbase. As tclederman pointed out the rear brake wheel cylinders are Huck type not Bendix which they should be, so I would surmise the rear axle is for a truck 1950 or older, possibly American GMC trucks have different wheelbases. The placement of the rear axle in an enclosed driveline setup is limited by the length of the driveshaft inside the tube, the rear axle must be positioned so that the driveshaft can engage the universal joint yoke at the transmission properly, there is not very much room to change the position of the rear axle and maintain the proper engagement of the driveshaft with the universal joint yoke. I would start searching for the proper rear axle with Bendix brakes and the correct wheelbase.
