Honestly, i can't tell yet.. I need some shims before i can use them. Also, only have 1 printed model, so not enough for the front diff and back diff. I'm going to order the hybrid front bulk and another printed model of the diff casings, so i can test these.
I'm confident the hybrid bulkheads are going to be strong enough, if anything they will need brass inserts for the threads. As for the diff casings, those are strong too, but i can't tell if these will be strong enough to prevent flexing and thus killing the gears.