I am running a mits alternator from a 3000 gt, its a 110 am unit, pretty compact and seems very reliable.

If I lost that many alternators I would look at the vehicles electrics. If you have a loose connection esp to the battery you can hurt the alternator.

When the alternator is putting out a lot of current and the load is suddenly (even for a brief amount of time) removed it cannot respond fast enough.

The regulator will drop down in its current to the field windings, but the magnetic field does not collapse instantly. So with out a load and a field winding at full tilt the output voltage rises very quickly.

There are Zener diodes in the alternator to take this load dump and shunt it to ground. However they cannot do it all the time and they will eventually fail.

Once you lose the protection diode the rectifing diode gets a nasty voltage spike and stops working.

Eventually you alternator is toast.

Also many rebuilds are not all that good.

If you can find out why the alternators died it can help a lot. It never hurts to check the connectors for high resistance.

Kevin