WW2 Relics from Germany/Belgium

[Jimbo]

Hi
I've recently visited a battle site on the German/Belgium border and have found the following items.
The battle was between US and German soldiers.
Does anyone have any idea what the aluminium pieces maybe from? They are possibly from an engine or gearbox as one of the pieces appears to have a sump plug? (This part has 'W 12 b' written on it).
Thanks
Jimbo