Interesting to hear that there are others who are also listening to Tucson '76. Although this particular performance has been underrated, I think the concert isn't bad at all.
Elvis' voice sounds pretty warm, soft and delicate, while also able to carry power ballads like Hurt. And there are other songs like Danny Boy (a real treat) and And I Love You So which are quite suitable for Elvis' voice at this period.
Something strange is that Elvis' voice changed in 1976. In October '76 Elvis often sounds a little raw on the ending of Hurt. Like on the album 'Bringing the house down' Elvis does the reprise of Hurt, but it sounds like his voice is a little bit 'strained'. Elvis knows this and proclaims his performance to be 'mediocre' but the crowd loves it anyway.
I can not hear this on the Tucson CD and the raw sound dissapeared after October and November of '76. In December '76 and the whole year of '77 he was very much able to reach the high note without hurting his throat too much.
I'm sorry that I do not know much about the Tuscaloosa concert, maybe there are other butterwings on this forum to answer that particular question. I hope you enjoyed the fact that I also like to share my experiences with you regarding the Tucson concert.