looking at it, i'd say its a normal open diff
i can't identify the plastic like bit at the top of it though
if it was viscous, i'd expect to see nearly touching plates on the outputs etc
helical i'd imagine would have some sort of gearing on it... but i've never seen 1 myself
also i wouldnt expect to be able to see into the cage at the planets and sun gears on a lsd... so open diff imo