I found out we use Corporate ring and pinions from this site while doing searches for "differential" and "gears". I also read that the bolt count is off of the ring, not the covers, so I guess that is another thing someone can hopefully clarify. The reason I am curious is because in my searching SPAZZ and/or Swordy mentioned the use of 4.88's which I had never heard of on an Isuzu, but surprisingly they show up when you look up some the GM ring and pinion sets. Along with, you guessed it, 4.56, 4.30, 5.38, among others. There are just a lot of things pointing in this direction it seems. If you do the searches I mentioned and dig through the posts, I think you'll see.