Probably not so much that your engine was shipped to Germany FOR the rebuild.
More then likely, the engine (and the truck it came out of pre-rebuild) was ALREADY IN Europe (again, probably Germany) when it was pulled and tagged for rebuild.
Then, it was simply depot rebuilt or contractor rebuilt and.... THE REST IS HISTORY.
As has been already stated in this thread, Uncle Sam maintained - and still does to some degree - large numbers of trucks and other weapons of war in overseas theaters, ready to keep the world FREE.
God bless America !
You just don't see other nations with that much invested on a worldwide scale.
It is only because of our changing posture in those international operations that WE get to enjoy so many surplus vehicles and other former USGI property.
Carry on.