Rear end housings different for 3 series vs 4 series carriers?

[Gibson]

I'm pretty sure I have 3.08s in the 12 bolt on my 78 C10 currently. I'm planning to moving to 3.73.

Were the housings different between those that came with 3 series carriers vs 4 series carriers?

I ask because my plan was to get a posi (open currently) and change the gears at the same time. I just don't want to find out too late it won't fit in the housing.

This is probably a stupid question, but I haven't been able to find anything definitive one way or the other.