alternator

We have a '78 marquis that we keep having to replace the alternator. They keep draining the battery. Any ideas on why?

Have you replaced the voltage regulator, also? this needs to be replaced every time you replace the alternator. If the regulator is shot, it won't allow enough voltage to reach the battery, in effect, draining it. Also, when suspecting the alternator, have it tested first, to make sure it's actually bad. :2cents: