Niagra has the cable but the end goes to the adjuster uses a pinch bolt in order to accomodate all cable lengths for various models. It does not look as good but it works.

http://www.niagaracycle.com/product_...ducts_id=10187

That pinch bolt/adjuster is also available separately for about $2.

Or you can make your own using a regular shifting cable. The end goes into the shifter takes the same Shimano cable ends. Then again you either need to use a pinch bolt or crimp a sleeve to make a stop at the adjuster end.

The shifter is harder to find new.

The newer Shimano Nexus shifter will work but the gear indicator is reversed.