What size is the rear sway bar on a lt1 z28?

Need to know. Im ordering new endlinks.

19mm.....:)

You don't need the swaybar diameter to order end links.

I was on thunder racing and they offered endlinks in different sizes... not sure why... but i thought i might be important.

They offer end links in different lengths.... but that's a function of whether your car sits at stock ride height or not, doesn't relate to the diameter of the bar. If you order sway bar bushings, they are sold based on diameter of the bar, and the u-bolt mounting clamps are sold based on the diameter of the axle tubes.