763C Keyless Start

I have an old style keyless start pad in my 1997 763. It has square raised numbers with 2 numerals per button. Downloaded a repair manual and user manual. Oddly I cant find any info on this keyless start control. No issues, would just like to know how to change code and general operation for this specific controll panel. Anybody have a lead on info for one of these old style keyless starts?

763C Keyless Start