Changing Glow Plugs on '87 300D

Actually asking this question for my Dad that owns a '87 300D.

He has been trying to figure out how to replace the glow plugs without having to remove the exhaust manifold. He's evidently having problems with the back 4 that he can't reach. Is there anyway around completely removing the manifold to get at them?

Also as a note he has had the recall done on the trap oxidizer which means he has the new redesigned manifold on there. Don't know if this has contributed to his problems or not.

Thanks for any responses/help for a newbie.

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Formerly 1975 Peugeot 504 GLD/Turbo Diesel hybrid
Currently 1997 Jetta GLX VR6