your '06 has 23 mm sway bar, like the SS's

 

X2 on what oldblue said.

Sway Bar Bushings - suggested by Snoopy with addons from 843de
- FE1:
>>> 2006 & 2007 production until VIN#3GNDA23P26S546471. Use GM PN 15822993 (which equates to a 23mm bar - energy suspension pn: 9.5159 (greaseable) - 9.5115 (non-greaseable))
>>> for FE-1 suspension after VIN#3GNDA23P26S546472. Use GM PN 20902784
(Note: my early early 2006 FE1 sway bar crudely measures out at 23MM so double check yours as the 1" bushings do not fit mine)
- FE3: Energy suspension poly for 1inch/25mm bar - greaseable - 9.5161 (9.5110 non-greaseable)
- FE5: Energy suspension poly for 23mm bar - greaseable - 9.5159 (9.5115 non greaseable)
------- GM - 20902785

 

some later '06 and up LS, 1LT and 2LT's had 25 MM swaybars.