instaling nav where is vss wire?

hey guys im in the process of installing my avn6620 and need to know where the vss wire is on a 2004 mustang not sure exactly where or what wire it is and also wondering if anybody with this same unit bypassed the ebrake wire by just grounding it out or used some sort of switch any help would be great

i forgot to post one here that its actually the orange wire already in the factory stereo harness