Yeah the snout is the easiest way to tell. There is a big difference between the diameters but unfortunately I don't have any (727 or 904) converters here to measure the diameter. If I remember though the 727 snout is right at 2" o.d. and the 904 is at least 1/4" smaller than that.
The pilot on the late 904 and the 727 are both 1.810", the early 904 used a 1.55" pilot (up to late 66, I believe) Just been doing research for a swap - cheech14
