I just double-checked.
I pulled out my 85 Combat (which uses the standard 75B slide), a 75B SA in 9mm, and a 75B DA/SA in .40.
As I understand it, the 75B .40 in DA/SA uses the same slide and frame as the 75B .40 SA model. If that is correct, the 75B SA in 9mm and 75B SA in .40 are not the same -- but they are very, very similar. Both are quite different than the standard 9mm 75B slide.
The .40 slide has a full rail going all the way to the end of the slide, while the 9mm rail is truncated at the end of the frame. Its very noticeable when looked at, head on. That could matter in a tight-fitting kydex holster, but probably not in a leather one. Neither would fit in a kydex that was formed to hold the 75B or 85B or 85 Combat.
The frames seem to be different only in that the beavertail on the 75B SA 9mm is curved up.
The .40 uses a Full Length Guide Rod, the 9mm doesn't.
When I compare a 75B/85Combat frame to a 75B SA frame, everything I can measure seems the same. The same seems true for the .40 frame, too.
(Note: I was using a digital micrometer to make the measurement -- but the display started blinking, indicating the battery was getting low. I don't know how valid the readings are -- but they were virtually identical until the blinking began.)