Ok, I'll order one of those cartridge install tools also. Definitely don't have one of those in my tool box.
Ignoring the threaded ends, the spindle appears to be somewhere between 119mm and 120mm depending on where I measure. The square ends aren't completely flat, so there is some room for interpretation. The only numbers that see on the spindle are as follows: 3P G-10 B. Is that of any help?
Will I be able to reuse my old cranks with the new cartridge style bottom bracket? I was thinking I could just use an appropriate bolt instead of the original nut.