Didn't see what specs you wanted for the 6 3/4's other than Pioneer. Here is a set:
Pioneer TS-G1643R 6-1/2" 2-way car speakers — for 6-1/2" and 6-3/4" openings at Crutchfield.com Cructhcfield will include the bracket to fit into 6 3/4 openings. Although the Kenwood's I bought from there didn't end up needing it.

Hopefully someone can speak up on how well they work, not too savy on quality myself. Only know what I've used myself. :-)

 

Do you need a bracket to fit the 6 3/4 holes? Cause on the website it doesnt say anything about needing a bracket...i found the same speakers cheaper on amazon so if theyll still work ill get them on there..

 

I can't personally speak for the Zr2 models, maybe someone with the same type as you can answer that. However, Crutchfields page does say in the second box below the pics of the speakers(look for the green checkmark) it fits with bracket for the front, and will fit with alterations in the rear.

So, anyone that drives a 2001 Zr2 wanna help 'em out with this one? I know I got lucky with my '99 4 door LT and didn't need the bracket.