Personally I would rather have boxes for the Western allies that aren't generic . For example , 25pdr ammo boxes , of both types ( charge & projectile ) were used by everyone for on vehicle stowage . The metal boxes were water tight with a rubber seal , and the inside dividers could be removed as various ammo types used the same box . IRC the 25pdr propellant box ( held 4 ) was also used for the 2 inch smoke rounds ( 12 ) that were fired in most British tanks and US Shermans . You see them welded on the turret rear of Shermans , and even in cut outs on the fenders of Canadian Stag Hound armored cars . Most 75 mm boxes were made of wood and there is a lack of them in period photos , probably cut up and burned to make tea or coffee .
Plus US rounds also came in cardboard style tubes , just look at any photo of a tank used as a mobile field gun in Italy , you see piles of them . There are also a few versions of the 6pdr boxes that would also be use full . On the German side , you only see ammo boxes during resupplyiing ammo as the boxes weren't deep enough to hold stuff and being wood , not water tight . You do see MG ammo crates as well as mine / grenade crates on the rear and fenders of Pz III & IV . Remember those fenders were very narrow so a large box wouldn't fit and you really didn't want to pile stuff up on the engine deck as it covered the engine fans and also kept the gun from targeting 360 degrees . There's an aftermarket niche for some resin company ,- 1/56 scale ammo boxes , there's tons out there in 1/35 and a few in 1/48 , I think we deserve some too