Speedo Cable Help PLEASE!

I have a 1964 dart with a 1977 360/904 trans in it and i don't have a speedo cable. the 64 speedo has the screw-on end and the trans has the plug-type end that is held in with a Y-shaped clip, almost like a distributor hold-down.
is there a speedo cable that will work on this combo or am i going to have to have one custom made? if so how much should that cost?
thanks!!!
-tim