The generic yet unofficial 'Art Deco' name would probably be a better identification, especially if it's a genuine 1942 truck: AK model code was just for the 1941 ½-ton model, (AL, AM & AM for ¾-ton trucks, AR for heavy-duty models, that year). If sure of a 1942 ½-ton model, it's then a BK, but it really looks like a heavy-duty model. And it has a GMC grille, but this could be due to the mod.