[Coco] NitrOS9 boot disk configuration question

[K. Pruitt]

I am in the process of making a new NitrOS9 boot disk for my Coco 3.  I have 
a Disto Super Controller II and I would like to take advantage of the 
no-halt feature of this controller as I do when using OS-9 L2.  The 
standard.bl file on the NitrOS9 disk has two drivers listed for Disto.  One 
is rb1773_scii_ff74.dr and the other is rb1773_ff58.dr.  I don't know which 
one to use.  So my question is what do the 74 and the 58 signify?

Also, for a real time clock I use a DS1216E chip plugged in to my Disto 
Controller.  For clock2 I selected clock2_smart as I am assuming this is the 
correct driver for the DS1216E.  Am I assuming correctly?

Thanks for any info you folks can provide.