It's the cable that runs down from inside your engine compartment. If I remember right its gray in color and goes into the drivers side of the trans, if I remember right it's more in the middle front of the trans. I haven't done one for a couple of years. Ask the guy you got it from if he changed the gears and to what ratio. Latemodelrestoration.com gives you a good gear chart to make sure you pick right.
He says its all stock he only rebuilt the engine and replaced the tranny and when he replaced the dash he said it was the gear behind the speedometer any ideas? Ive been looking online and have no idea what he means
I changed my cable out last summer. Start with a new cable. Id go ahead and buy the correct ratio gear as well for the part that goes into your transmission. You will start by taking off your cluster shroud inside and removing your actual cluster. Its a pain but not too complicated. The cable itself comes with lube instructions from the manufacturer. Run the end in through the firewall and if simply clios onto the back of hour cluster. Then run it underneath the car along the firewall and be sure u keep it from rubbing or touching anything hot. Simply goes I nto the drivers side of the tranny