Hi guys! Can someone tell me the part number for an alternator of an Vectra C Z22SE and it has 100 Amp or 120?

Also, the cheapest anywhere?

My car is a 2002 Saloon with automatic gearbox and full option if that can help in term of Amp usage and 1 time it didn't worked anymore.
After that, when I went to service to check it sometimes it worked and other times it didn't so the electrician told me it's a liability and needs changing, anyone else had the same experience?