You can use the later model truck alternator. Bolts right on. The pulley is 1 rib wider than the stock one, but the stock belt fits the grooves just fine and doesn't try to hop around. I've been running one on mine for several weeks now (emergency fix, didn't have a pulley to swap on) with no issues.
However, you should be able to go into a parts store and order a ND 160A alternator w/ the correct pulley. I think you need to look it up for a '93ish 2.5, and it should give you several amp options, like 65, 95, and 130 or 160 or something. Anything over 100A should be the ND.