Slant 6 904 parts for v8 904 ?

I don't know for sure, as Most 904's I have worked on, are the earlier ones. However, I am under the impression that all late 904's have the wide ratio, low 1st gear and are lock ups. There is a 904T which is basically a truck 904, but I don't know what the difference is. Check the numbers on the pan rail of both transmissions, then you should be able to determine what parts interchange.
PS: There are different designations of the small TF. 904, 998, 999, and 904T. Some internal parts will swap and some will not.
Example 904 has a single wrap rear band. 999 has a double wrap rear band. the case is different.
Again, I,m not sure on late models.