I agree, I was at this show, it was at the New Haven Coliseum. Also I only remember Muddy Waters opening the show. I don’t remember Grinderswitch, and the other shows on this tour only show Muddy as opener.
I believe that the show was at the New Haven Coliseum, not the New Haven Arena. They did play the N.H.Arena in April 1972, with Berry Oakley, but from 1973 on, any concerts in New Haven were at the Coliseum.