They list on the site, but not saying much, since two other potential resources listed as specific, yet they were 40s.
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(Translated:Anyone want to save me from pissing into the wind?)
Like I said I’ve never seen a 55 Ron Davis radiator in person but I have seen Ron Davis custom radiators a lot more complicated than a 55 radiator and I know Ron Davis will build you whatever you want and you should expect it to arrive at your door step exactly as you ordered it. A call to the shop will get you all the information you need to provide them with all the information they need to build you an exact drop in unit or you can send them your OEM radiator and let them get the critical dimensions, either way they are capable of giving you exactly what you’re asking for at about the same price you quoted to patch you old unit but the Ron Davis unit will be head and shoulders better.