Hy Wada, my advice would be to replace all the steel and rubber lines on the truck and the front two wheel cylinders as well, then you would have a whole new system. Personally I would use silicone [DOT5] fluid when I bled the system, but that's a personal prefference, if you do decide to do that make sure you ask the wheel cylinder provider if their cups are compatable with that fluid, hope that helps.
