Hey Gary, does it list the height of the rad in your catalog? The one in my car is short for sure at 15". None of the top sealing parts come close to to the top of the core. It appears to be like an inch short. If you look at my left side pic you can see how big the gap is under the baffle bolted to the core support. Also, I've noticed that the aluminum OE rads have minimal tanks on the ends...they do not protrude like the brass ones. That would make sens with the vertical foam end seals. Does your catalog show straight or curved top inlet pipe?
As far as flushing, the PO had been restoring this car for many years. When I bought it the engine had been rebuilt and recently installed with all these new parts including the rad, clutch fan etc. He told me when he was sorting out the over heating they had replaced the old clutch fan and installed the new Delco unit at a shop which had tested it. They said it improved the running temp. I dunno...but from the clutch fans I've replaced, they typically spin very free when cool if they are bad, or leak oil or make a ton of noise. This seems proper. Plus I've added the electric fan to the front. I think part of its overheating issue is a lack of proper sealing to the core support and shroud, but since it appears too small you cannot get it to seal using the stock sheet metal parts and foam.
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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?