Eaton dst/rst41 rear swap interchange

Had the rear diff destroy the spider gears in my Pete the other day. According to Peterbilt my truck has a Spicer/Eaton/Dana dst41 power divider front, and a rst41 rear. I can't find anything local to save my life. I've been told/almost sold by lkq on a rs402 chunk. I can't confirm if ds/rs402 chunks will fit into a dst41 housing. I've got a ds404 diff that's the right ratio on hand, and it looks like it will fit.
2 questions
Will a ds402 diff fit in a dst41 housing?
Will a ds404 fit in a dst41 housing?


Make it 3 questions.
Wtf Dana/Spicer/Eaton/Hastings/clevitte/perfect circle? Can't you pick a company name, and a product model and stick with it?