Alternator wiring questions

[NITRO]

the red wire that comes outta the part that plugs in on my alternator goes to the stud on the back of it, then from the stud, another wire (10 gauge) goes back behinf my engine and i think into the firewall. but, on my brothers blazer, the red wire comin outta the top doesnt go to the stud on the back, but he cut it after i can see all that cause he is gettin rid of it.so, my question is where does the wire that comes outta the top of the alternator right beside the white wire go to??thanx

NITRO

 

[tipoil]

the red wire from the plug go to the stud behind the alt the brown wire go to the 'charge' lamp in the dash