item n°39 of the Altaya/IXO "1/43 Main Battletanks of the WW2" - 10.5cm le FH 18/1 L28 auf Waffenträger Geschützwagen IVb "Heuschrecke 10" prototype, Germany, 1943.
The German 10.5cm leFH 18/6 auf Waffenträger Geschützwagen III/IV ‘Heuschrecke IVb’ ‘Grasshopper’ was designated a weapon carrier (waffenträger) and not a self-propelled artillery gun. The reason for this is that the turret could be removed from the top of the modified panzer IV tank chassis by a block and tackle rig attached to a movable metal frame.
The idea was that the gun crew could keep up with the armoured Panzer Divisions. When needed to fire as an artillery battery, to give long range support firing high explosive shells over the heads of the German infantry and tank crews, The gun would be removed and placed on the ground where it could be fired like a normal artillery gun.
The heavy lifting metal framework could be swung upright into position by a hydraulic system or a manual back up system. When not needed it was lowered down and stored on top of the upper track guards on both sides of the tank chassis.
The vehicle could carry 87 high explosive shells. If more were needed the turret could be removed and placed on a gun carriage and towed behind the tank chassis. This allowed for more ammunition to be carried onto the battlefield. The modified Panzer IV tank chassis became a turretless armoured ammunition carrier. This configuration would have only worked in gentle undulating countryside or on roads. The gun carriage wheels and frame were carried on the tank chassis at the rear.
The 10.5cm howitzer could also be fired from on top of the tank chassis. There was no top to the turret. There were a few disadvantages of an open topped vehicle. The crew was exposed to the elements and were also at risk of injury from enemy thrown hand grenades, mortars and shrapnel from air burst enemy shells. A canvas tarpaulin rain covers was produced." (Tanks Encyclopedia)