You need to have a couple of letters preceding a 6 digit serial number located at the base of the generator/alternator base in order to answer this question. Please look closer and try again.
2004
1967 1500cc
1971
1973 , 48hp , 1600cc
1960 1200CC
1957
This would be a model year 1967 Type 2, or bus engine.
That is a model year 1971 through 1973 1600 cc engine.
to find the year, you need to know the letters prior to the number
1600cc from Model Year 1971 - www.lennysvw.com
This would be model year 1963.
try - bustopia.com