The setup with the internal pump is a speed differentiaing diff with clutches. GKN and Dana are two companies that come to mind as producers of these kinds of differentials. I've worked with the GKN - the internal pump is a shear-plate pump design that builds pressure (uses an isolated silicon-based fluid inside the differential housing, separate from the regular gear oil) to push a piston that pushes on clutch discs. The pushing on the clutch discs is what "locks" both wheels up. Once both axles (wheels) lock up, the speed differential from side to side diminishes, which slows the relative motion of the shear plate pump plates, which drops piston pressure and lockup action. Pretty slick. I would assume that the Dana is configured in a somewhat similar fashion.....pretty straightforward.
This worked very well on the slippery surfaces that I tested it on, but I do not know of the long term real-world durability or performance in a race-oriented vehicle.
Hope I didn't make that clear as mud.
