On mine, the AC ground and neutral connected to a little bottle-cap like doohicky on the inside exactly opposite the DC ground wire connection. The AC hot connected to the circuit breaker on the generator. To get at them required removing a bunch of the secondary parts inside (the control/regulator boards, starter solenoid, mounting plate for the circuit breaker/fuse/start switch, etc.). It was pretty straightforward, everything using the same size Torx screw and having connectors to unplug where needed, but it did take awhile to undo everything.
I don't think disconnecting it from the junction box was practical on my installation; I think the wires run straight to the transfer switch, though I may be mistaken I haven't come upon an intermediate junction box, at any rate. Your installation may well be different, of course.
