The 2" - 2.5" lift is right between the 8" and 10.5" autoLYNX size. The determining factor is your front bump-stop length and shock stroke length. If you have at least a 2" bump-stop extension installed in the front, you can/should run the 10.5" version. If you do not have bump-stop extension installed in the front you will need to run the 8" version. 2" bump-stop extensions are common with most lifts that include a 10" or greater travel shock. 8" autoLYNX works w/ 7" - 9.5" travel shocks and no added bump-stops. 10.5" autoLYNX works w/ 9.5" - 13" travel shocks w/ at least 2" front bump-stop extension.