65 Barracuda A 904LA trans. leakage problem

If you cannot find a cable, and IF you can get the cable out of the rear of the trans, get some heat shrink tubing, that has sealer inside. Put it over the cable, and heat it with a heat gun. That will seal the leak. If you try this, I highly recommend you get a factory service manual, and read the procedure for removing the cable. Do it wrong and you will open a can of worms.