Nice pair of trucks, ABetterName! Thanks, Rhade and Eswube (you must be thinking in a book with your polish aircraft
Another Krupp heavy gun, but certainly not one of the real heavy ones: 21 cm Morser 10/16.
The first one is a Morser 10 with shorter barrel and depicted with shield as it was during the shelling (the shell shown is the APHE one) of the Liege forts at the begining of WWI. The second one is a Morser 16 without shield and with rubber tired steel wheels, for motor traction. It is shown as it was during 1942 summer, during the long Leningrad siege, with an ordinary HE shell for soft targets. Cheers.