Bill you (and my uncle) are of course right but I figure it can't hurt as I have no idea how bad/good the PO (when not drunk) treated this engine/truck. I have run across many a weird thing on this truck. In fact I just installed two adjustable bar supports across the radiator near the tank front and aft. The PO butchered the radiator support for the longer 55/235 he did not understand that the radiator cross member holds the fenders from sagging and stops the radiator from splitting apart. Chevy had a lot of problems on the early models and thus the X bracing and the 54's had the top channel. The ZDDP its a feel good thing that makes no sense but then again hobbies never make much sense, that's why they are hobbies I guess. :>) T/C Steve