I am pretty sure that the Disk ][ connects to a set of pins on the back of the ///.The blue port all the way on the left is where it would go.
Um, nope. That is the Disk III connector. It is a 26 pin connector (25 pin on the III+). The Disk II has a 20 pin connector (or DB-19). So as I pointed out, it is NOT directly compatible with a Disk II. Apple did this on purpose to force Apple III buyers to buy the new drives rather than just replace the CPU and use with their existing peripherals. At a minimum, the pinouts have to be remapped. The first 20 pins of the Disk II & Disk III seem to be identical in function, suggesting that the 6 remaining Disk III pins are utilized solely for daisy-chaining up to three Disk IIIs. If this is the case, then only the connectors need be swapped as with the original Disk II to DB-19 connector for use on the IIc & IIGS.
vintage photos show Apple employees with Apple III's with Disk II's hooked right to them
I'm not sure that is proof of a Disk II being hooked right to them, without any modifications. This
prototype is a perfect example of what was likely going on in-house while the /// was in development and likely even after the Disk III came out – the modified Disk II, or Disk III prototypes would not have been replaced with production models.