Choice of alternators

[pattieG]

Alternator on my 52 plate Fiesta 1.4TDCi is whining. There seems to be two choices of alternator. One rated at 80amp and the other at 150amp. How do I determine which one I need? I've looked on the alternator itself but can't see a part number anywhere.

[T1pper]

Give the reg number to someone like euro parts they should be able to tell you what the correct alternator is also I would imagine any ford dealer.