You misunderstand what 848 or 838 means. It's shorthand for 848000000 or 838000000. These numbers refer to how far drawbars get pulled out, starting from the left.
IOW, pull the 16' drawbar out to 8, the 5 1/3' drawbar out to 3 or 4, and trhe 8' drawbar out to 8. This gives you your lower manual jazz setting. If your XK-3 has a pedal drawbar coupler to the lower manual, you can add it for more bass in the lower 2 octaves.