These old (initial) schematics are the only one available for the public, and I'm very sure about this.
Agilent and later KS did / do not publish schematics anymore, so updates aren't available either.
That was already the case, when the 34410/411A came out.
Maybe you should contact KS support directly, if they can provide these schematics to you, personally..
For the 34410/411, these documents were available for some time on a hidden agilent folder, on request from a customer, obviously.
Frank