I would suggest doing all the wheel cylinders and the three rubber lines. I would also look at the hard lines very carefully. You will need a tool for installing the brake springs. Also it would be a good idea to leave one side together until the other side is done. That way you can compare the two.
Darrell,
I think truckernix nailed it. A complete inspection of your brake system is in order. If you replaced the master cylinder a while back it should be fine. The rubber hoses fail from the inside to the outside and they're inexpensive. I'd replace all three of them. If the hard lines are in rough shape, replace them too. You might be able to find some at your FLAPS or you could purchase a pre-made brake line kit from one of our vendors. Another approach is to buy the hard line and fittings from your FLAPS to make your own brake lines. You will need a flaring tool and and a quality one in order to produce brake fittings that don't leak. Since the LF shoes are soaked with brake fluid, you might as well get all new brake shoes while your at it. Examine the locks on the pins. If they've been used several times they may be thin or break when removed. Review the manual: brake spring tool, brake fluid, a length of 1/4" tubing, a container for holding the brake fluid that you bled out of the system, etc.
Remember, your life is riding on the brake system and that's the last place you want to take the cheap way out.
