i really doubt that they installed an angular contact ball bearing in there.
Skid, i'm curious as to where the difference between DGRBB and RBB came from.
The 15 degree contact angle which seems to be the maximum for the "Conrad" style of ball bearing, produces the mathematical relationship that the maximum thrust (axial) load of the dgrbb is one half of the maximum radial load, the ratio of which is exactly accounted for by the fact that all of the balls make contact for axial loading at 15 degree contact, but only half of the balls make contact for radial loading and of those, the distribution of radial load has a predictable coefficient. . anyhow, i did look into this myself when i found the folks on the cnc forums trashing the conrad style bearing as unable to support any substantial axial load, this isn't the case at all. its just that, bearing manufactures are cheap and microns do matter.
6203 bearings are extremely cheap, but i wouldn't be putting 2$ bearings in a hydro turbine.
you may want to look into ceramic bearings, do you know yet why they failed?