Haynes manual wont answer anything as they are rubbish.
Just go back to the garage and ask them whats what.
I would say the mot man has just listed the failed itme under a general heading, could be the panhard rod which ois the arm that attaches the front axle to the chassis
Mark stick your location up and a local landyzone forumer might come and point you in the right direction
Google defender parts manual, then upload it, once done search for drag link and you will see a decent exploded pic.
Lynall
Lynall