After I put the changes into Tops-20 Kermit to recognize Ultrix and properly check protocol, I finally got around to testing it against few hosts on HECnet.  As I had dimly recalled from the late 1980's, Ultrix supports Tops-10/Tops-20 NRT, viz:

Kermit-20>c nofar/st
[Remote system NOFAR:: is running ULTRIX-32]
[KERMIT-20: Connecting to DECnet node NOFAR::]

and also:

Kermit-20>c ostara/stay
[Remote system OSTARA:: is running ULTRIX-32]
[KERMIT-20: Connecting to DECnet node OSTARA::]

Sure made my day!

When I finish wringing some more bugs out of Kermit-20 (I'm redoing the parity routines to use string instructions), I'll see about testing against Ultrix in addition to Tops-10 and older versions of Tops-20 Kermit (I've got them going back to the 1980's)

SETHOST currently cannot connect to these hosts as it reports incorrect configuration messages.  That's probably an easy enough fix.