I have recently acquired an IBM PC RT, and I lack the keyboard and mouse for it. They use an odd 6 pin connector. The keyboard is just a model m with a different cable, but the mouse is proprietary to the RT.

If you haven't heard of the IBM 5080, I wouldn't be surprised. It's a high resolution color graphics system made in the mid 80s for CAD and other graphic programs. The 5080 doesn't refer to any specific product, rather the whole system. The system consists of a few components:
IBM 5081 color monitor
IBM 5083 pen tablet
IBM 5085 graphics processor (basically a fancy graphics terminal)
Light pen
Lighted button panel
I am not sure of the model numbers of the last few items, but you can find pictures. Of them occasionally on Google images.
In addition to all those things, there is a breakout pod that attaches to the bottom of the 5081 monitor that all the accessories attach to.

I have the original manuals for the system, so I'll post some scans of the accessory pictures.