I tried getting a cable from Imperial Services earlier this year and finally gave up after 3 months of waiting. If there still making cables there not easy to get.
Are you looking for the Imperial floor shift cable used with the 65 floor shifteror the column shift cable. You realize that an internal mod is done to the valve body. I have both style of cables and the modified valve body still installed in my 904 (never installed in my 65 GT).