Volkswagen Repair: altenator, rebuilder, alts

Question
have a 81 jetta volts,gas eng w/fuel injection need to fiqure out right altenator. the last one at a junk  yard gave me the wrong one. mounting didn't match can't tell what liter eng is, it is 4 cyl and i think its 45 amp not sure.shouldn't all 45 amp altenators have same mount housings. i think they gave me 65 amp ?  

Answer
Leonard,
I'm not sure about this but I'd think all 45 amp alts. would be the same. Maybe they used Bosch and Motorola alternators resulting in a different mounting between the two. You might be better off taking your original alternator to a local rebuilder and have it repaired...could be as simple as worn out brushes. Good luck!