Technical Odd Zenith Carb ID?

I got these three Zenith Carburetors along with a ton of other stuff from a guy cleaning out his late father's barn. He didn't know what models these were or the application and neither do I. They're BIG. The smallest one is still bigger than a Model A carb. I think the two monsters with the angled mouths may be marine but I just don't know... so, I'm asking!

Have at it:

 

Need numbers or any other casting info.

 

COE GMC on the lower left. Others are truck or tractor - Carbking can tell you everything you need to know.

 

Here are some numbers to help from Carbkings website.

 

I haven't found the numbers on these yet. Where did Zenith usually hide them?

 

Most non-Ford Z's have a circular plate swedged or riveted into the carb with tiny, indistinct numbers...you can see these in the 2 cabs closest to camera in last pic. The number of Zenith models and variations thereof is ASTOUNDING.

 

I hadn't even noticed them, THANKS! I'll pull them out again and take a closer look.