Barb- I would think that a generic SmartWheel driver could be made to work with some study & adaptation. Do they have such a thing or is their junk customized for every application?
Ken- I think the device you are looking for is called the VDC or Vehicle Data Computer. It is referenced in a file on the ACA Tech Library
page under Chassis, see Annunciator VDComputer Bulletin. I don't recall if it mentions a manufacturer. If not, and you are an ACA member, check w/Mark Harrah to see if he can scare up a contact.