Do you mean the axle tube?? Don't know what you are refering to as "Chunk".The numbers 707340 are stamped on the front pass side of the housing between the pinion seal and the housing bolts.
There is an axle code stamped (not cast) on the center "chunk" of your axle. It's on the left front side on the flat surface where the bolts are. If you post it, someone here can look up the ratio for you. I have a couple '55 to '59 rears with the
code AF, wich is 3.90:1. Most likely what you will have as well.
