It’s funny this is brought up. When I was at Bethel in the 1990s in the “office furniture department” my overseer called me and another guy to his office to take care of a very sensitive project. Lol
We were told we had to move a file cabinet from 30 Columbia Heights to an actual vault in the tunnel of 124 Columbia Heights which is literally down the block.
We were escorted by 4 brothers who handled night security at the 30 Columbia Heights building. The cabinet was duct taped, shrinked wrapped and a chain run through the handles of the cabinet with a lock between the links.
We were told that it contained the records and correspondences of brothers and the congregations records of those in areas the work is banned and under persecution.
Was this march down the block with this cabinet overkill? Definitely, but they took that shit seriously.
Soooooo I doubt there will be anyone willing to give you much info about what you are looking for