I was supplied with a pair from inwood models in the UK.

They leaflet that came with them told me they were the same servo as the 8411, but were suitable for use on 6V rather than 4.8v. (Or if were being pedantic, i can check if it said 5 cell nicds rather than 4 cell nicds) It even gave torque figures on 4.8v versus 6V.

I can certainly check if i still have the box what they meant.