Walter,
why don't you simply write to the MoD and use the Freedom of Information Act? Ask them all about whether ZD576 was fitted with and/or carrying any additional equipment.
That should give you the answers you seek. If they write back and refuse to confirm/deny, then that will have to be dealt with at the time.
I hope this can remain the dignified campaign it was meant to be.
Good luck with your questions.
Kind regards,
Brian
"Justice has no expiry date" - John Cook