How to test alternator out of car?

[sun tortise]

Alternator in my 1981 240D is electrically OK, but has seriously ovalized mounting holes, so it sits very crooked. I have another alternator that looks good, and has bushings so no ovalized holes. Can't remember where i got it. Is there a way to test it out of the car with a multimeter before installing it to find out if it works? I am thinking it was pulled for a reason, but maybe the V.regulator was bad, which i could just switch from the known working one.

Also, how does one switch the pulley and the little finned fan under the pulley without mangling either?

Thanks in advance, you fellow Mercedes victims have always pulled thru for me!