Need help ID'ing NP203

[66gmcguy]

Hello folks. I just picked up an NP203 on a trade because I need the range box off it. After I tore it down, I realized this seems to be a little different than most pictures of 203s I've seen. The differential cover is 1 cast piece made of iron, instead of the two aluminum pieces you normally see (see pictures.) So why is this one different? It has a 27 spline input so I guess that rules out it being a dodge or ford case? I unfortunately didn't snag any pictures of it when it was all put together.