Here's a chart:
Green Caps:
1966-1969 with 225, 273, and 318 engines and 48 amp alternator
1968-1969 with 340 engines and 48 amp alternator
1970-1973 with 225, 318, and 340 engines and 46 amp alternator
1973 with 400 engines and 59 amp alternator
1974 with 225 and 318 engines and 48 amp...