as stated, hydravac 1st, BUT, you also need to loosen the upper brake shoe on each rear wheel all the way before you start, otherwise it will trap air in the wheel cylinder. Here is a link to the online manual for a 55. I am not sure which side your hydravac is on, my 55 has it on the pass side, my 58 it is on the driver side so the "farthest wheel" may be the opposite side than the manual depending on your truck. I also built a pressure bleeder that makes it a lot easier!
http://chevy.oldcarmanualproject.com/shop/1955truck2/55ctsm0507.htm
