The only controller i have seen with 3 wires was on a freezer with a cascade system that went down to -80.
I can`t remember the case make, but when I was talking to the maint guy on site he had simalar probes spare in a box that were for ....?(Icant remember)

Why dont you measure the resistance of the probe and take a temp reading, then take say a dixell probe and do the same , now make the probes read the same by adding fixed resistors in line or paralell.
and / or calibrate the dixell?