Found this in the FAQ section of the curtis website, not of much help though: Did you try to send them a email, don't know if they are willing to help:

FAQ:

When trying to pick out a controller for my application, I see the desired model has some missing numbers. For example: 1204-2XX. What does the "XX" stand for?
The "XX" is a designation number that tells us what options are configured on a certain controller. Some of these options could be certain error detection configurations, software differences, or even an exclusive controller for a certain customer. We have some internal documentation which helps us figure out which controller would best fit your needs.

I have a motor controller that failed. It is a 1244-4401. I have an extra one on my shelf, but the model states it is a 1244-4403. It looks exactly the same as the old one. Will this work?
This is a tough question to answer just by looking at the model number of the controller without any supporting information. More than likely this will NOT be a "drop-in" replacement. Usually there is enough of a difference in the controllers, even though not externally apparent, that you will have some type of error occur. You will need to contact a Curtis representative and they will be able to research this and find out if it is possible to replace one controller with another.