Oculus, I checked the plug-in configuration for the Type 561S vs the Type 561B and yes, there are differences. The Type 561S does have some additional interconnects not found on the Type 561B. So I opened up the extender to check how it's wired and found this. All 24 pins are wired even though some aren't used. So this extender WILL work with a Type 561S.
So if you friend want's it he can have it for the cost of shipping. Let me know and I'll get it in the mail this week.
In other news. Banging my head against the wall trying to figure out why the Type 2B67 Time Base plug-in won't trigger. And why am I having such a difficult time? Because the fucking schematic and manual don't match the unit. Don't know how many times I've run into this with Tek stuff. I looked to see if I could find other variants or updates to the manual but so far no joy.