i'd go with a red lensed marker lamp for the light.. not a resistor.. and certaintly not a zenir diode. that's asking for trouble. a REGULAR diode.. sure.. but not a made-to-avalanch zenir.
if you want a dash light.. get a dash light.
for the lamp inline with the alt #1 a 168 or 194 will work fine.
for a diode.. a 1n5408 will be mor ethan fine.. and radio shack 276-1661 and 276-1141 are ok. in practice.. and 50piv/1a diode will work.. but 200piv and 3a is way superior.
the diode will have a marked side. the marked side goes toward the alt.
strian relif it or it will break the leads off the case.