The rear axle assembly is a hypoid, semi-floating type, where the centerline of the pinion gear is below the centerline of the ring gear. This allows the outer rear tire to turn more quickly than the inner tire when the vehicle goes around a corner. The axleshafts are splined to the differential side gears, so the inner tire turns its side gear more slowly than the outer tire. The differential pinion gears roll around the slower side gear, driving the outer side gear and tire - more quickly. The differential is housed within a casting, known as a "carrier", with a pressed steel cover and the steel axletubes are pressed into and welded to the carrier. An optional locking limited-slip rear axle is also available. This differential allows for normal operation until one wheel loses traction. A limited-slip unit is similar in design to a conventional differential, but includes a series of alternating clutch friction discs and plates which slow the rotation of the differential case when one wheel is on a firm surface and the other on a slippery one. The difference in wheel rotational speed produced by this condition applies additional force to the pinion gears and through the clutch friction discs, which are splined to the axleshafts, equalizes the rotation speed of the axleshaft driving the wheel with traction. Due to the need for special tools and equipment, it is recommended that operations on these models be limited to those described. Where repair or overhaul is required, remove the axle assembly and take it to a rebuilder, or exchange it for a new or reconditioned unit. Always make sure that an axle unit is exchanged for one of identical type and gear ratio.