I changed all 4 door speakers and the speakers in the back were marked with a + / - so there was no problem with polarity.

on the front doors the speakers had no polarity anywhere on the speakers. The front right had a dark blue and a light blue wire, I used the dark blue as +.
On the left front there was a brown wire and a yellow wire simalar the the two rear speakers. I used the brown wire as positive after i compared the old speakers front and back and they were almost the same so guessed the tabs would have the same polarity.

Does any one have the speaker wiring info for a 2001 blazer with foor doors?

Best not to just gamble on your installation.

If you don't know, DON'T DO IT AND WAIT!

Good guessing.

LT GREEN +
DK GREEN -

TAN +
GREY -

DK BLUE +
LT BLUE -

BRN +
YELLOW -