Thanks Jane, good work
Great info there, and now recall that the first two stages of the, by then defunct, J-91 became the fan for the turbofan version of the J-57/JT-3, i.e. the TF-33/JT-3D. Since the inlet diameter of the that engine was around 53 inches, your figure for the J-91 seems borne out.
Still would like to find some pics of the J-91, and am also still wondering how/why P&W managed to use the same designation, JT9, for what now seem to be TWO COMPLETELY SEPARATE(!!!) gas generators, since there is no way the core for the JT-9D turbofan could have been 50+ inches in diameter at the first stage after the fan? BTW, does anyone out there know where one can find cutaway views of any of these powerplants?