speedometer cable help

[GM Muscle]

i have a 70 chevelle and ordered a mechanical autometer speedometer. the chevelles cable is a clip on style and the gauge is a 5/8-18 thread. the square drives are also different sizes. do they sell and adapter. or do i need a new cable? part numbers?
thanks in advance.

[GM Muscle]

i found a part number for the cable this morning. CA-3004
hope this helps anyone thats looking..