It looks like a crank was neither standard equipment nor an option or accessory on most Advance-Design trucks but, as Jed stated, it looks like it was available in 1947 and might have be available into 1948 (as least with the 3103 Commercial, Utility vehicle in 1948) - see link to the Master Parts Catalog, below.

A crank was available from 1937-19...model. (thank you Kieth Hardy for TOCMP)

How/where is the crank positioned on an A-D truck (through the center hole in the front bumper)?

Tim