Picco letting you know the weak points eh? Don't know if it is the same, but a lot of 1/8th scale diffs are interchangeable. You may have to drop in the whole diff assembly with the ofna pinion gear.
I have Hot Bodies LSP Pro diffs in my Kyosho, little heavier but stronger. Much cheaper too.
I can't tell you if the ring gear will fit your buggy's diff cup though. You are going to have to have the parts in hand or know someone who has tried it already. I would not waste much on that Duratrax. It will keep breaking.