Will an alternator from a 2000 Chevy blazer fit 2002 s10 blazer?

The fitment depends on the specific engine in each Blazer. A 2000 Chevy Blazer and a 2002 S10 Blazer are very similar, but S10 Blazers are generally smaller trucks. Alternators are engine-specific, not vehicle-specific.

To know for sure, you MUST compare the alternator part numbers. You can find the part number on the alternator itself (usually stamped on the casing) and look up the correct part number for the engine in your 2002 S10 Blazer using a parts website like AutoZone, Advance Auto Parts, or Napa Auto Parts. Then compare that number to the alternator you have from the 2000 Blazer.

If the part numbers match, or if a cross-reference shows they're interchangeable, they'll likely fit. If they don't match, they probably won't fit, even if the vehicles are similar.