I can't seem to find a 99-00 Si rear swaybar for sale anywhere, but I found one off of a 98 GSR for $60 + shipping. I also found a 99 Integra LS rear swaybar for $40 locally.

Are either of these compatible with my 97 civic EX, the way the 99-00 Si rear swaybar is? I know they're both 14mm, vs. the 13mm Si bar.

What else do I need to install these? Si endlinks, bushings, brackets, etc.?

 

i was running a teggy rear bar for a while.

you will need the brackets that mount flat (si brackets i think) to the subframe rather than the integra brackets which have a stepped design to mount to the subframe properly. i couldnt find the flat mounting brackets so i used big-*** washers that stacked flush with the frame side of the bracket.
as far as endlinks, the stock integra ones mount directly below the ends of the bar, which are just slightly too narrow to mount directly to the stock endlink holes in the lca. i think the si endlinks, which mount to the side of the bar would line up right.
or there is this option for DIY endlinks which will accomadate the difference in spacing.