Well, a table of pointers to unit info objects is located at 0x4E1348. It's indexed by map_id so you could do something like:
int **unitInfoArray = (int**)0x4e1348;
int *cargoTruckUnitInfo = unitInfoArray[mapCargoTruck];
for example to store the pointer to the cargo truck unit info in cargoTruckUnitInfo. I think if you look at the HFL source code there is some stuff in UnitInfo.cpp that might be helpful (and that class may be a cleaner way of getting at the data anyway, it has a bunch of premade functions so you could do UnitInfo truck(mapCargoTruck); and then access it with some functions on the class, or you could just grab its internalPtr that gets set up... which reminds me, I would like to finish HFL someday perhaps.