Need an EVO module for 1997 Expedition

I am planning to convert my LLS to a standard suspension. At the moment, the LLS also controls the power steering. When I do the conversion, I will need to replace the module with a standard EVO module from an XLT Expedition to retain the speed sensitive steering otherwise it will revert to full boost which is dangerous at highway speeds. Does anybody know of a source maybe on the net where I could find one? I hate to guess how much it would be at the dealership. Thanks in advance. D. Punch