You've probably got two Hydro-Vac units on it, one for the front axle, another for the rear. While it's possible to bleed the brakes by pumping the pedal and adding fluid periodically to keep from pumping the system dry, it's a lot better to find someone with a pressure bleeder and pay them a little to get all the air out of the system.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!