new alternator

put new alt. in my 69 dart from 93 dodge truck 120 amp. Do I run 8 gauge wire from alt to battery or from starter relay to battery? and does battery disconnect switch play any part in this? thanks in advance

Thats alot of amps to go thru the bulkhead here is what I did.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml