If you don't need the vacuum pump feature of the Hitachi LR-series alternators, you can put on any alternator you like.
If you want to use someone else's alternator and still have vacuum for your brake booster, you can add a
separate electrically-operated vacuum pump.
If you need the OEM-style alternator driven mechanical vacuum pump, your stock Hitachi LR150 alternator is rated for 50A output -- under test conditions, which means full-field voltage at a specific output voltage. If you are testing at a higher voltage than the rating, the current will drop off.
IMO, 50A is
plenty, unless you have some special electrical loads. Certainly, 50A is enough for the stock SD setup and is not especially overstressed. Even the all-the-bells-and-whistles luxury all-electric Maxima has only a 60A alternator. Do you have a big winch or a huge stereo? A rack of high-wattage lights on a roll bar? Those are situations where a higher-output alternator would be useful.
The simplest swap is for a LR1
60 alternator from a Maxima (LD28) diesel. It is a bolt-on, with a single wire different (the LR160 has an extra terminal that would remain unused in your swap). The LR160 is a 60A unit. Much more information on the LR-series alternators is in
Hitachi LR150 50A alternator thread and
Hitachi LR160 60A alternator thread.
I have seen someone hang a
second Delco alternator up above the injection pump, on a SD22 at the JY.
You
might have a rebuilt alternator that has the common "broken diode" problem.
