First off let me say I really like your weathering and the build itself is just great.
The markings are non-descript so all I can mention is that you also did a great job on those, looks like someone actually went up and hand painted them on.
I agree with Dino on the mag and taillights, I just want you to see the dukw taillights.

Of course as someone likes to say the devil is in the details. The slots you see on the sides are for drainage but were not added until after the war. They should be smooth like this;

I added these other 2 just for your reference;


On the markings you should know they are almost all completely different for each campaign so if you decide to make a specific DUKW remember to check your references.
Just a great job all around, congrats,
Bob
I don't know a bunch about the artillery piece so I wasn't going to say anything but you also did a great job on that, Really great details on it.