Re-reading this thread, something leapt out at me... It mustn't have done them much harm; Darragh E. Nagle, later co-founder of the Santa Fe Institute, lived until he was 94!
Hi, studying "The Hugh Bradner Films" ( in the very end ) I have found the the footage of the Sherman in the moment of modification and testing. See the # on the turret. To my mind it must have been leaded yet as the suspension arms are close to horizontal , equipped with new turret hatch door and with no gun barrel. It will be also interesting to know the name of the person corresponded .
Interesting. I've seen the picture below captioned along the lines of "Groves and Oppenheimer at Ground Zero of the Trinity Test the day after the bomb was exploded."