The thick red one attached to the insulated post is the alternator output and goes to the electrical system and battery for charging. The thin one is the field wire use to energize the rotor windings through the dash alternator light. The alternator body is grounded either through a strap or by the bolts to the engine and its grounding straps.

I hope this helps.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.