My 57 car generator apparently has a bad bearing as it howls when cold & when I put a stick on it & against my ear it feels really rough, & seems to be overheating in just a few minutes. I have a spare, both  have the end plate # FAS 10139-B The original also has the #B6A 10002-A on the case. ( One or more of these #s may be Canadian manufactured ) Questions- Unfortunately the spare has a smaller pulley with a slightly different offset, so it does not line up with the other pulleys. Why ?  Can I change the pulley ? Are they right hand thread? Also are the front bearings still available & are they pressed in?  ( please, no alternator conversion advice! My car is on a stock "vintage plate" so an alternator conversion is not a legitimate change.)  

Paul