Whats up with the Vortec 350's and the replace the timing cover deal ? I just tore apart my old engine that expired and on the plastic cover it says "Replace assembly upon removal" , the new rebuilt I bought has no seal or gasket for it , everything else is there . Do you really have to but a new one ? I would think I could use a gasket maker type of sealant so it wont leak , but I would hate to put it all together and have it fail. What have you all done in this case ?