I have an AT&T 630 MTG computer terminal that is sadly lacking a keyboard. The keyboard it needs is an AT&T model "56K 420 ADA", AT&T part number 501004865. It would have been made around 1983-1987.
It looks like this:
I just missed one on eBay, argh! Serves me right for not looking sooner.
If anyone here has one, can you please drop me a line? Thanks!