I'm thinking maybe since there was no load on the rear wheels due to no rear shafts, your center diff was just transfering half the power to the front wheels and the other half to the driveshaft/rear diff. May not have hurt your center diff at all.

with a LSD rear shouldn't all of the power gone to the good shaft anyway?

well when mine went out all i had was nothing my car woulent move at all i mean i could hear stuff grinding

When there's no load to the rear wheels it will tend to accelerate slower and take more to keep it at the regular speed to throttle position than usual. (I know this because Ryan and I had to run the racecar like this for the tracks that wouldn't let us run AWD before we had the VCE) More than likely you burnt some life off of your viscous coupling than anything. I'd open the rear casing on the old diff just to be sure you didn't hurt it as well.