There have always been specialty tributes that not only highlighted classic shows, performers and artists, but not-so-coincidentally plugged shows still running on Broadway (or currently touring at the time of the broadcast). There were performances from revivals when the category did not exist and performances from non-nominated shows because of the status of the performers. I went as far back as the 70s and did not include the plethora of novelty numbers from classics that were not part of the Broadway or touring seasons.
1971:
1776 (part of the 25-year retrospective and currently running on Broadway)
Applause (part of the 25-year retrospective and currently running on Broadway)
No performances from any of the nominated musicals
1972:
No, No, Nanette
1974:
Lorelei
Good News (revival to open on Broadway 8 months later)
Purlie (briefly revived during the season)
1975:
No performances from any of the nominated musicals
1978:
The Act
1979:
Eubie
I Remember Mama
1981:
A Chorus Line
Ain't Misbehavin'
Annie
Evita
Sweeney Todd
Woman of the Year
1984:
The Rink
1988:
Bennett tribute including performances from the currently running A Chorus Line and the original cast of Dreamgirls (though the show also had a flop revival that season)
1990:
"Special Salute" including performance from the currently running Cats.
1991:
"Special Salute" including performances from the currently running Phantom of the Opera and the current tour of Bye Bye Birdie that failed to reach Broadway
1996:
Big
State Fair
2007:
Fantasia sings from The Color Purple
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian