The indicator cable has nothing to do with what gear your actually in. The shifter linkage could be out of adjustment though, not putting the trans fully in park. I'm not sure on the exact adjustment procedure though.
EDIT: Here's how to adjust the shift linkage.
https://www.ford-trucks.com/forums/8...djustment.html There's also a few links at the bottom on how to adjust the pointer and fix a sloppy shifter.