I was replacing the insulation blanket's for the entire acon bay with a new type ,the job came with some SRM drawing's which indicated pack #3's conditioned air split after the water separator.I'm fairly sure if you look in R/H BLG WW (-400) you can see evidence of where the duct would pass through the bulkhead in the same position as the APU bleed air duct on the left,there was no indication of type.I'll try and find the photo of the elev befor the split was introduced, it was probably during testing that they changed it,what about the 76 split.