There were 727's put behind slant six cars too. What you need to do is look at the pan, if it juts out a little where the dipstick tube is then it's a 727, if it's just straight then it's a 904. Both utilize the same valve body though, the only thing that might stop you from putting a 727 valve body in a 904 or vice versa is the middle rear attaching bolt hole in the separator plate might be for just one application or the other. The hole in the separator plate can be elongated though as most all the shift kits with replacement plates have the hole elongated to fit either trans.
