C/30 rear wheels locked up, no fluid

[phillip24fan]

So I'm starting to work on my grandpas '70 C/30 dually that has been sitting for years so I can get it running again.

Front wheels spin freely when jacked up in the air. I then jacked up the rear axle into the air and neither side will spin or budge at all. The brake pedal goes all the way to the floor with no resistance.

I even had the truck idling, (rear axle airborne sitting on jack stands) and the engine would stall every time I tried to put it into 1st and make the wheels spin. That's how stuck they are!

Here's a pic of the master cylinder when I took the cap off. The empty part is for the rear brakes correct? If so, why would the rear wheels be frozen when there is no brake fluid being fed to them?




I'm not very familiar with brakes so any help is much appreciated. Does it look like I need a new master cylinder? Or should I just try bleeding the rear with fresh fluid? I was planning to pull the wheels off tomorrow and bang on stuff and see if the drums will break loose and spin free as my first step.

Thanks!
-Phillip