If this is the special hosted by Kathryn Crosby and Gene Kelly . . .

. . . and if you can believe the source (available here,) it first aired around 1979.  Another "internet" source listed here under post #11 also shows that it aired in 1979.  There is yet another web page here that also shows it aired in 1979.  Not really an exact date, but at least it puts in in the ballpark.

I wouldn't stake my life on any of these sources by any means, but it appears that 1979 is within your speculative time frame.  An educated guess would be sometime in late November or December 1979.

Too bad that TV Guide didn't scan all of their old listings from back then, eh?

-=Perry

I did find on hit from another magazine   Weekly World News   Dec 12-18 1981

There are the TV listings showing this show on NBC   Monday Dec 14, 1981   9 pm.

The bad news is that does not prove it was the first or the only showing,   just that it was shown in 1981
I got no other hits though.

look HERE

Thanks for the help.  It really is a shame that TV Guide doesn't maintain a database with all their old issues.  I know there are people who collect them...too bad nobody has undertaken the project.  That would be a terrific resource.