Here is info from John Denver's(see Himself below) John was on the Tonight Show 15 times.
Twice as a Guest Host.
"The Tonight Show Starring Johnny Carson" (15 episodes)
... aka The Best of Carson (USA: rerun title)
Episode dated 18 August 1972 (18 August 1972) - Himself
Episode dated 19 September 1972 (19 September 1972) - Himself
Episode dated 25 January 1973 (25 January 1973) - Himself
Episode dated 10 January 1974 (10 January 1974) - Himself
Episode dated 11 January 1974 (11 January 1974) - Himself
Episode dated 27 January 1977 (27 January 1977) - Himself
Episode dated 16 October 1978 (16 October 1978) - Guest Host
Episode dated 4 May 1982 (4 May 1982) - Himself
Episode dated 26 August 1983 (26 August 1983) - Guest Host
Episode dated 24 May 1984 (24 May 1984) - Himself
Episode dated 20 December 1984 (20 December 1984) - Himself
Episode dated 29 May 1985 (29 May 1985) - Himself
Episode dated 3 March 1986 (3 March 1986) - Himself
Episode dated 3 December 1987 (3 December 1987) - Himself
Episode dated 19 October 1990 (19 October 1990) - Himself
this was a response from a poster on the Carson board. so, if anyone has the money time and inclination , here you go.
I alos wonder if carson still has a web site, you know lots of deceased stars do, and if he does, I wonder if they could answer this, , Surely someone has asked them this before.
for myselfm I saw the show. I know Denver was on it, and I know they did talk about jws. I just can't give you a blow by blow account. it was widely discussed the next day, by jws. today, it would have been on CNN.