You should be able to use a common metric crowfoot wrench to loosen the IP lines. There are special wrenches for removing tubing connections, I forget the name for them, and there are crowfoot versions of them too. Removing glow plugs from a 602/603 is usually not difficult as they are not the long skinny things that the 606 uses. Be gentle, drive the car first so the engine is warm, put penetrating oil on the glow plug threads for a few days before you try removing them. Use anti-seize on the threads of the new glow plug.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970