Hello Phil!
I've seen this photo before! But I didn't realise those were engine transport containers, thanks for pointing that out. Unfortunately I don't have the measurements...
Looking at how they probably filled them with dirt and used for revetment I wonder if that was a good thing to do... I mean I suspect somebody was missing those containers, they don't look to be meant to "discard after use" and suppose you get a new engine, what do you do with the old one? It probably should be shipped to be rebuilt, right? I mean in a container, right?
I hope somebody's got the measurements or knows where to find them. And I bet there's a NSN for this container, and that would allow us to find at least the basic dimensions.
Good luck with your search and have a nice day
Paweł