NutLoose,
AFAIK there were no external signs. What you call the 'afterburner cans' I knew as 'module 12'. It is wholly contained in the exhaust, after the low pressure turbine and only visible when standing directly behind the engine. Also a bugger to remove/refit requiring a specially made extra long 11/16th (if memory serves) spanner and usually a forearm full of cuts and grazes after job completed.
Hope this helps.