will a 2003 alternator for a nissan maxima work in a 2004 nissan maxima

http://en.wikipedia.org/wiki/Nissan_Maxima They changed the body style from 2003-2004 but that doesn't mean the alternator is necessarily different (by that I mean a 2008 Maxima Alternator would be the same as a 2004 - but likely not a 2003)......so I would say just call a parts warehouse and ask them to look up the 2003 then write down that part number - then have them look up the 2004 and compare part numbers! It could be something as simple as replacing a pully - but with as many Maximas are on the road it should be cheap to find the correct year Alternator.

Make sure they are the same size engine too.

Well for the 2004-2008 they all have a 3.5L V6 In 2003 they offered a 3.0 V6 and a 3.5 V6

Would a 3.0 cylinder 2001 Nissan maxmia alternator fit on my 2.3 cylinder 2001 nissian maxmia ??

Look up both parts and see if they are the same or not.