Hi All, while waiting for an adapter to fit our 2001 Ford f150 overflow bottle to arrive, to pressure test the radiator to find a coolant leak, I spoke with a neighbor (old retired mechanic) about the ongoing problems I have with our truck. One of the problems is an on-again/off again vacuum leak. Can't find any broken vacuum or missing vacuum line so we are going to do a smoke test to confirm the leak(s) location once and for all. My neighbor said that one place these trucks leak is the intake manifold?? My neighbor said that means a lot of work just to change a gasket. He also said if we have to do that job, and we find out the manifold on our truck is plastic, that we should definitely go to a junkyard and get an aluminum one and replace it. He said no-one sells new aluminum ones anymore and the plastic ones are crap! Does anyone know if this is true? How would I know, before doing the job, if our truck has an aluminum intake manifold? I know that plastic parts can get brittle and warp, especially with the heat of the engine, so if what he says is true, I would rather just get the aluminum one. Does anyone know what year and model Ford's with the 5.4L/2V engines, that would have the aluminum intake manifold? My neighbor said there might be some E150's, some F250's, possibly some Excursions, and even some Ford passenger vehicles with the same motor. Also, are the 'lower intake manifolds' made of aluminum, or some of those plastic? Gonna beg my son to come over and help me for the couple of days it will take me to try and get everything done on this truck once and for all! Any and all advice is greatly appreciated!!