The part number for the push button for the 6138-0030 is 80610269. None of the 6139s in my 1979 casing parts book use the same pusher. You can probably use any pusher and it will probably function. The difference will probably be in the overall length of the pusher with some cases requiring longer ones. If you match up a case requiring longer buttons with those from a case requiring shorter ones, it will work but may look funny. Given the ease of removing and swapping pushers, you might as well try it. You can always use the "wrong" ones until you find the proper set.