I've sure with some handy work you could get the TTR 2-speed kit to fit.

LOL, a savage 2-speed? Just don't say anything else is all I can say.

I am not sure that HB came out with a 2-speed conversion kit, but if you can find the measurements of the 2-speed itself, and your center diff mounts, I am sure you can get one from another car to fit, such as the TTR one.