8 3/4 posi unit change

not always the case. 2 wd D200s could have either depending on package and year. Even the W200s didn't always come with dana 60s. Some got 9.25 corp in some years, 8.75s in the mid to late 60s, and even dana 44s in others after the 8.75 was discontinued.
my 76 w200 had 9-3/4" dana rear axle. I don't think I've ever seen a 5 lug 3/4 ton, or an 8 lug 9-1/4" full floating Spicer. I havent seen it all, yet, but it would have to be rare for sure.