904 question

So assuming a slant and a 318 904 form the same generation, are all the internals interchangeable?

I have a core 318 904 that needs rebuilt. I can get a rebuilt many years ago and never installed slant 904 for 80 bucks locally. Can I swap the slant 904 guts into the 318 unit?
After almost 40 years in the transmission industry, calling upon all manner of transmission rebuilding facilities, I've never seen a "rebuilt 904" for 80 bucks. Oh, pardon me, there was a less than honest shop, that bought cores, stuffed them in the parts washer to clean them, changed the pan gasket and filter, and then painted them all nice and shiny, but even he wanted more than 80 bucks.