<VV> Generator replacement not working

[Charles Birchwood]

Hey all, just replaced my alternator on my '65 Monza coupe with an alternator 
off a parts car that was working. I put it on and turned it over  and everything 
was running fine, then my voltmeter showed the system jumping from 12V to 16V 
and my alternator light came on, any ideas?
 Charles Birchwood Ps. 121
"Nullius addictus judicare in verba magistri"-Horace