ZH, the standard fit in the 60s was 2xRS S-band and one L-band. From what you are saying in the 70s and 80s they were usually 3xRS.
What I have seen though is 2xRS and a blanking plate on the 3rd position.
On the X-band jammer, this was a rapidly deployed Mod after the fortuitous recovery of the Skip Skin radar. The RBW was also tuned that radar. One problem was training as the frequency range of the jammer was outside the range of British AI radars, ie no training mode.
We had to train against the F4E. While BEagle has a point, we were not fighting against the F4J etc.