I have an 8x8 MIDI i/o box with a keyboard connected to it on MIDI input 5.
I want to get with it and use Simple Instrument Tracks but cant figure out how to drive it with my keyboard so I keep doing it the old way with a discreet midi track.
 
 
TIA!
 
 

A simple instrument track has a midi input and an audio output. Setting the input port isn't any different from doing so on a regular midi track.

The MIDI controls not shown on the instrument track are in the MIDI tab in the track inspector

Thanks, I looked in the inspector and couldn't find it.
I'll try harder.

It shouldn't matter for the Inspector but possibly your track view filter thingy is set to something that doesn't show I/O (like "FX"). Make sure it's set to I/O or All.

At the bottom of the Track Inspector for an Instrument track ar two tabs, MIDI and Audio. These tabs give you access to two types of track parameters. But as Sander mentioned, if the Track Control Manager is set to show 'All' or 'I/O' controls, you should see the Input field for an Instrument track in the track pane as you would with a MIDI track.

T'was not set to "All" - now it is and there they are!
 
Thanks now.