I am looking at a 1945 mb for a possible project.
I have only seen pictures so far and before i go look at it in person
i have a question about the fuel tank.
I can see what looks like a boxed out area under the driver seat,below
the body tub.
I know the fuel tank is under the seat but the tanks i have seen do not
go any lower than the tub.
Is the mb a larger tank than a cj2a??

The larger tank under the fuel tank is for water. You will see a radiator type cap at the rear, just ahead of the rear tire. This is the drain. The water was to quell fire from a hit on the fuel tank under combat conditions.

Thanks for the reply.
The more I learn about the mb the more
unique features I am noticing compared to
the cj.

The Cj2a tank is smaller 10 gallons as opposed to the MB or GPW tank 15 gallons which has the lower section that sits down in the sump that Jack described. Its also a commen problem area for restorers as it is often rusted out.

Makes more sense now, I had heard the area referd to as a sump before but wasnt sure why.
Is there replacement sheet metal available if this area rusts out??

Yes all the panels and the sump are available. They just spot weld in.

Does anyone have photos or diagrams of what the in-tank filter and the associated fuel tank look like? Is the late mb tank identical to the 44-45 tank or is the an extra access hole for the filer?

I dont think ther was an access hole. If you have the holes on the firewall then it had the filter mounted there. If not then it was the tank one.
This is from the G503 site.

The top and bottom of the filter was made from thin (1/8 inch), circular pieces of porous, bronze. These circular bronze pieces were then soldered to the center portion of the filter which was made of sheet metal. The filter was attached to the inner fuel pick up line by flairing the line after the center part of the filter was attached. My guess is that the inner fuel line and fuel filter were assembled as a unit before they were installed in the tank. This must have been done before the sides of the tank were put on.