speedo cable

I bought a set of dolphin guages, but it did not come with a speedo cable, i have a th350 , where can i get one? i checked bauto zone and napa, also how many speeds does that tranny have , it sounds like 3 to me, i was running about 2600 rpm at about 75 thanks

th350s are 3 speeds. youc oudl pick the cable up at a junkyard maybe? im not sure, have you checked summitracing.com or anything? they might have what youre looking for. good luck!