A little help with my future engine swap

[Valveguy]

I have a 74 Duster with a Slant six. I did the Clifford set-up which was ok but my engine needs a rebuild/refresh. Instead of a rebuild, I like the idea of putting in a 318. I have a leftover automatic transmission from my 72 Dodge Demon (original). I know that the slant six transmission has to come out so would the 72 automatic transmission fit into my 74 duster (original slant six) easily? I'm not sure if the 72 Demon transmission is a 904 or the 727 or if that even matters. Does anyone out there have any fast answers?

Thanks!

 

[jaws]

bolt in with the 318. Same drive shaft if it's a 904.