Replacing my speedometer cable

A cable with a plastic clip on one end is for 68 and later speedometer. 67 and earlier have a collector nut to screw onto speedometer. That later plastic sleeve and clip does align and support the cable better. Best we can do is snug up the nut.
Clean the hardened contaminated grease crud from the speedometers square drive port before poking a new cable in there. Route the cable to the instrument as straight as possible. Forces form the cable in any direction is what kills these instruments.