I installing a rear sway bar on the back of my chevelle which i purchased a hotckis sway bar which does not come with any type of shims would i need to purchase these for the sway bar installation and can anyone tell me why they are needed. Thanks

Sway bars shims are not always needed. You would need to see how "loose" the bar fits between the lower control arms to determine if you need to
"shim" it. Shims are sometimes needed to mount the bar so it fits without stretching it to the control arms.

Mike