!966 Dart Speedo Screech!

I've got an A-833 OD tranny with a 360 V8 in a 1966 Dart Wagon. I've got a speedo cable that screeches like crazy! I've cleaned out the casing,greased the cable, trimmed it to exactly the same length as my other '66 Dart Wagon (A 833 +SL6, that doesn't screech) and I give up. Any suggestions out there? It sounds like it's at the tranny end, not the speedo end.Thanks.