On mine, the only lines I had to deal with were the brake booster line (plastic nipple on the plenum), EVAP line (plastic nipple again) and a line that goes from the intake hose to a metal nipple on the other side of the throttle body on the plenum. I can see the nipple for the brake booster being brittle and breaking, but that's about all. Maybe there are more on older GP's or supercharged?