http://www.imcdb.org/vehicle_977696.html [...]
"Based on..." without model name, link nor picture for comparison when talking about a truck which cab isn't visible sounds more like a guess than like a real identification...
Clearly 2 different models: there's a cannon and dual headlamps on 978593, not to mention the kind of box on it's front face, while viewing slots (or whatever their name is), mirror arms and side "windows" are obviously not the same. Why should they be merged?