I can answer if the car is set up the same as a 1995 Z34. The alternator is hidden on the backside of the engine between the firewall and engine block. Some genius decided to put it there, and they even have a flexible duct hose to provide cooling air to the alternator.
It is necessary to remove the two large engine mount (rear) bolts and drop the engine down about 10". It pivots on the two front engine mount bolts, no need to remove them. Dropping the engine down is necessary to get the old alternator out, and the new one in. You also need to remove the front Right wheel/tire. Behind the tire is a plastic/rubber cover on the inside of the fenderwell that you must remove to get to the alternator mount bolts on the pulley side.
It takes about 4-5 hours to change the alternator. Our alternator has failed three times in 10 years. This poor installation job by the Chev engineers costs us two ways:
1) The alternator fails due to poor airflow.
2) It's a SOB to change.
I Suggest buying a Chiltons or Haynes repair manual, be cause the answer above is obviously not going to help you.
Actually, an 84 is a rwd model. The alternator should be on the front passenger side of the block. There are only a couple bolts holding it on. Unplug the wires that are plugged into the alt. The top bolt is an adjuster bolt. Undo that to take pressure off the belt. You may need to slide the alternator a bit on the adjusting mount/bar that the alt is bolted to on the top. Remove the belt, remembering how it is routed on all the pullys. Then remove the top bolt, and then remove the bottom bolt. There may be a spacer on the bottom bolt, so be aware that you don't drop it and remember its position for reinstallation. The alt should just come right out. The total time to replace should be only between 15 min to an hour, depending on the bolts being "stuck" or not. WD 40 may need to be used on them before and after removal.
I've owned an 80 Monte with a 400, and an 82 with a 350, and had 2-3 alternators fail between both cars, so I got kind of good at swapping them out.