I bought one second hand about 6 months ago, but I have not changed the wiring on mine. I dont know if you talked to these people or not, but it looks like this may be the part you are looking for. and the link for the page.
http://www.shootnhunt.com/catalog/JM...e/5201336.html
MOTORGUIDE STANDARD MOTOR REPLACEMENT PARTS CABLE
Description: 84" Foot Cable
Manufacturer MOTORGUIDE
Manufacturer part number 9384
J&M Catalog Number 5201336
Your Price $16.41