They are from 1997-2002. Do you know if there are some available for a 1991 ? Thanks
Just by looking at them you can tell...
If they look like what you got, then they'll fit.
They were only used in Brazil for 1997-2002 (reportedly) but they should replace any composite reflector used on the GMT400s here in the US. I have, however, not confirmed this.
There are at least four of us on GMT400 that have these. I can attest that they fit my 1998 Suburban. I would have to check with the other guys to see their model year.