http://home.4x4wire.com/erik/diffs/#rear4cyl Turbo and V6* 4Runners and mini-trucks use the Toyota 8" 4-pinion differential in the rear. This diff is known as the "V6/Turbo diff." It has larger carrier bearings, is generally stronger than the standard 4cyl version, and is a direct swap into axles that use the 4cyl 8" diff. Separate gear sets are made for the V6 style diff (only from Toyota and Precision Gear), but cheaper, more readily available 4cyl style gears are commonly made to fit- the only difference being a very slightly larger pinion gear on the V6 style gear (the actual strength difference in gear sets is debatable). The strength increase in this diff over the 4cyl diff comes mainly from the beefed up housing, which stiffens the entire assembly, keeping the gears in proper (stronger) alignment.
Although somewhat rare, there is a version of this diff that came from the factory with
4.88 gears. The carrier (3rd member housing) has a different pinion offset so that the ring gear doesn't need to be as thick. This means that no gears other than the factory 4.88's will fit this particular diff. However, diff cases, commonly called carriers (factory, LSD, lockers, etc.), for the standard V6/Turbo diff should be interchangeable (4cyl and V6/Turbo carriers are NOT interchangeable).
* A few V6 trucks and 4runners have been found to have come with the 4cyl style diff from the factory. Nobody knows why.
