Im not a differential builder on a regular basis at the shop Im at, other guys here at work are though. I only do differentials from time to time. Im just basing my opinion on what I have seen come in and out of the shop doors in regards to the toyota 8" differentials that are built here. Some were probably lower quality metallurgically compared to a 1990s oem toyota ring and pinion set, but some too were name brand gears too which I would assume rivaled the metallurgy of 1990s toyota gear metallurgy.Yeah except my opinion is rooted in math and engineering