I was about to write what Glen just said; I've had mine apart and Bob's right, not much there. A worm gear and a pinion gear on 2 perpendicular shafts and the support bearings; the housing bolt hole pattern's eccentric compared to the cover, which is how you adjust the lash.
Helpful hint: if you ever do take it apart, scribe a line on the mating pieces so you orient it the same way going back together or that lash adjustment may take forever...