You can do it with classic straight wrench.
You will need a 8 (metric size) wrench to disconnect the wire and then a 12 wrench to unscrew the glow plug.

You can remove the injectors pipes to have more room but if you take into account the time required to performe that, I'm not sure you will save time !

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1984 240D running well
1981 240D not running
1978 300D almost a wreak ...