Just stay as far away as possible from the units (alt or starters) sold by AutoZone.
Lifetime warranty, but after changing them yourself several times, you'll offer to commit suicide.
When the starter on my '94 Suzuki went out, I bought an AC/Delco from O'Reilly's.
Much cheaper than the OEM, and never had any issues with it.
Twenty years ago, you could plan on an Alt, starter, or water pump going out at 70k +/- 5k miles on any GM or Ford. Like clockwork. Obviously some would last longer, some a lot less. I don't have enough firsthand knowledge to know if that's changed much, but it appears that they may be lasting a bit longer these days, but failure at any mileage above 60k doesn't surprise me, and I wouldn't be shocked by 50k or 120k.
Oddly enough, when I had to replace the starter on a '92 Saturn, the price of the AC/Delco installed by the Saturn svc dept was less than the part price alone of the trash sold by AutoZone (that I priced just for comparison).