Yes, they're the LOSB3528 Heavy-Duty Differential Case: 8, 8T, LST2, XXL/2. Very clever design and eliminates the spider gear axles cutting into the plastic.

Hope 0verkill doesn't mind too much I'm polluting his thread, but here's the measurements of the stock Losi 8ight ones I took once for someone - HD ones should be same as it is drop-in replacement. All measurements below are in mm. I think the Durango DEX408(T) has metal insert diffs too, in case anyone's looking for alternatives.