is this a 904 or 727

Actually, both are correct. A body 4 speeds (and Volare / Aspen overdrive 4 speeds) are shorter, the same length as a 904. B and C and I think E body 4 speeds and truck / van overdrive 4 speeds are longer, and are the same length as a 727. You can use the longer 4 speed in an A body by fabricating a plate to re locate the shifter to where it would be with a short (A body) 4 speed.
http://www.bigblockdart.com/techpages/abconv.shtml