The metal units are I believe original units. The new units are a type of plastic. BUT here's my story. I changed my unit and it was not the problem. The problem was that the Exhaust Gas Return channel from the EGR valve to the air intake plenum was blocked. I cleaned it out and spent $7.00 ojn a new gasket and fixed the problem. I think the engine code was PO302 or Po 304.You should get a check engine light if either is acting up.
