Robinson Racing Blackfoot ball differential

I purchased this set in a little hobbyshop in Strongsville, Ohio. It was in the 50% off bin. The retail price was $90 but the store owner sold it to me for $35. (Incidently, more than 50% off. Who am I to argue with that?.) Anyways, I am looking for a Blackfoot to stick this baby into. It will fit my Frog, but I'd like to keep it original, separating bevels and all.

This set includes more than just the ball differential. It comes with the center spur along with the universal drive shafts and sliders. It appears to be very robust. No one ever talks about this ball diff set. Mostly, people are paying top dollar for the Thorp unit and dogbones.

This has been installed in a project and I will have pictures up soon.