I did the swap today. I did because I needed more power.

The swap went smooth and I did it very cheap. I bought the bracket from a dealer $40-50. The alternator came from a junk yard off a '94 Caprice (with the 5.7L of course). It only had 40K miles on it. I paid $30.
Bought a 4 gauge battery cable to replace the wimpy charging cable (GOT to do this) at the local parts store for $5.
Grand total is $75.

I measured the output (hot) to see the improvement. I had EVERYTHING running electrical I could. The CS-144 alt put out 94 amps at idle! Wow, was I impressed. My volt meter on the dash never dropped below 13 volts either.

 

John, the only downside of that is that you'll be hitting the battery really hard. It will shorten it's service life considerably.

 

How could I shorten the life of the battery by swapping the stock 105 amp alternator for a 140 amp alternator?

I would think it would increase the battery life.

 

John, you might want to consider a high capacity battery with a high output alt. Problems is this, a high output unit hit's the battery with a very high initial charge after a cold start. This is not the type of charge batteries like. My wife has a high output unit on her Blazer and it goes through a battery every 3 years or less. I have worked a lot with lead-acid batteries for the last 20 years and the best type of charge is a slow long one. One thing I can you that will prolong the life is once a month or so trickle charge it. My 89's original battery is still in service in a neighbors car. With a very fast high current charge the battery never really reaches capacity. The high current charge very quickly brings it up to terminal voltage but the battery lacks the capacity it is capable of. I use a cheap cigarette type trickle charger and once a month plug in all the cars overnight. If you consider doing that you will find the battery in conjunction with that new alt will work well together.

 

Thanks Danno. Nice reply.