It is confusing for us small truck guys.

I have a 54/55 2-ton GMC and I suppose it is, in general, like your system.

Most likely your system is a vacuum-assist system, using a hydrovac unit.

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0525.html

One thing to keep in mind is to adjust and bleed the system as described in the Shop Manual.

1. The hydrovac bleeding procedure.
2. The wheel cylinder bleeding procedure.

I decided I'd spend the money on a new master cylinder and new wheel cylinders and new brake shoes (all from Rockauto.com, I think). You might not have to do that.

More big-truck-knowledgeable people will post wiser/better opinions/advice.

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.