I'm pretty sure the radiator in my '62 CJ5 (Dauntless conversion) is from the mid 60's. I've flushed it once with a single application of Blue Devil Flush. After draining, flushing with water, filling with the flush product and driving around for a few days, it did come out muddy brown. There's still a good bit of corrosion/deposits in the passages however. I haven't ruled out another flush with a specialized product, but my guess is that they have less aggressive acids so that they can be used in aluminum radiators. Unfortunately the neighborhood radiator shops are few and far between around here so the old rodout method is probably not an option. Does anyone have a chemical/procedure for aggressively cleaning the crud out of old copper and brass radiators? Muriatic acid? C-L-R? Vinegar? Oxalic acid? Sulphamic acid?