Thanks for posting the pics. You have some history info for her? Love to hear those stories about where they've been and what they've done.....for 60 years.
If you haven't heard the "what you gonna do with that" question yet ??????
Mileage?
Last time used, serviced?
If she sat for a while and you are going on public roads it's hubs off and at the very least an inspection of all rubber in the brake system. No need to add brake fluid until all your mechanical checks are done because you could just be pouring it into a hole.
As we all know if one cap, line, hose or fitting pops while braking you loose the option of stopping. My mechanic buddies reject rubber that shows signs of moisture/sweating or cracks.....correct decisions are usually the most difficult and expensive on old trucks.
If you're still testing then it's easy enough to crack a bleed screw at any backing plate and have soldier b push the pedal a little. "The differences between Dot 3 and Dot 5" is easy enough to find out.
http://www.advancepetro.com/differentbrakefluid.htm
I drop all fluids on a truck I don't have a history on so I know the brake fluid has not boiled.
Some more detailed pics of that plow assembly would make this plowboy very happy and thanks for sharing on Steel Soldiers.