2011 and later GM trucks equipped with four-wheel drives will be found with three different types of IFS (independent front suspension) front drive axles. There is an 8.25” ring gear and two different 9.25” ring gear front axles. The 8.25” and one of the 9.25” axles are the “suitcase” type of design using two aluminum case halves that bolt together containing the ring and pinion, differential carrier and other components. The other 9.25” unit is a Salisbury (Spicer design) with a one-piece case with a removable case cover, which is used in the 2500 and 3500 HD models. The aluminum split case design has been in use for many years and the 9.25” Salisbury type was introduced in 2011.