mc3k series , mc31k series and mc32k series share the same keyboard pcb. The problem is that some units come from factory with kb set up on autodetect and others set up to a specific kb. If is set up on auto you can change any kb to any kb , for example from 28 keys to 43 keys by just replacing the keyboard , if is set specifically to a specific keyboard then you need a config block . The config block contains all the hardware information about the unit, including display , scan engine , gun , straight etc... so you need the exact part number config block that matches the unit , the wrong config can brick the unit. To check if the keyboard is set up on auto, go in settings/proprieties and scroll to config info , and down to keyboard type , and under hex it should be value "80" , if is 80 then is set on auto , if not then you need a config block.