Chet, I don't have an answer for your adapter question, but do recall a discussion on this on SCOF a while ago. The consensus was that the cable should not wick trans
oil up to the speedo. The usual fault is a missing O-ring or a reverse wound speedo cable. There is supposed to be an O-ring inside the screw-on collar where it goes on the transmission, and that O-ring is needed to keep trans
oil out of the cable assembly. Another problem is that some replacement cables are wound the wrong direction which can cause the wicking of
oil. Compare the spiral of a new cable and the old cable. Most people with these leaks solved the problem by replacing or installing the O-ring, removing and wiping down the cable, and in some cases, replacing the cable with one that is wound correctly to not allow wicking up to the speedo. Do a search on SCOF and there are probably more threads on this, I'll try and check too, good luck, hope you get the leak fixed
