As Whiz points out in his link to John Farley's article on GR3 INS alignment carts on ship, someone had worked it out well before the Falklands erupted, as I'd always thought.
When it was all going on, we were flat-out night & day at Dunsfold on other mod's , and no doubt various sub-contractors were too; we were much later told by then Test Pilot Steve Thomas, " none of it reached us before it was all over ", though I'm not sure if that includes the AIM9L fit for the GR3's, will have to refer back on that - age creeping on !
www.harrier.org.uk
is well worth a look.