'94 Olds 98, alternator part # question

My mother has a '94 Olds 98 that the battery keeps draining on after we jump start it. Seems by searching the forums this is a common issue. When I jump start it and the car is running, if I remove the battery cable, the car dies. I'm assuming the alternator is bad. I have attempted to find a replacement part on the salvage yard sites, but then I do a search I am asked to pick one of three different part codes for the alternator. Can anyone tell me how to know where to find this info? I removed the alternator from the car, and took down the Vin #. The engine is a 3.8L. But I can't find any of the numbers the salvage sites ask for....I even looked the alternator body itself over....all I found was Delco Remy and one three digit number.

Pulling the battery cables when running is very, very old school. You need a voltmeter to test the charging system, battery, etc. Google parasitic drain. You'll find 100s of how to and probably a bunch of videos. Could be something as simple as glovebox light, trunklight etc.

You can get a new alternator from Rock Auto, Remy #91327, 105 amp, 12 month warranty for $86.79. But first charge the battery with a battery charger and test it 'off' the car. Then test the alternator with your multimeter with the engine running. Go to AA1car.com For step by step help on this. HTH

Look at the housing of the alternator....amp rating of it will be stamped on it....

As suggested, check the output with a voltmeter.....make sure you have power at the large red cable to the alternator(fuseable link is not blown)...