Alright the pencil style retrofits are in, however the W115 chassis the temperature sensor for the glow plug relay has two wires: one that connects to the plugs themselves, and another that seemingly leads to the relay. The issue is there is no ground strap on the engine. Is the ground built into the large metal piece here?

EG:


On the left, the piece with the black wire attached to it has two wires coming from it: one to plug number one, and the other to I assume to relay. With these new retofitted plugs I need to eliminate the ground, so is this it?

Regards,
Kyle

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1976 300D
190,000 Miles
Colorado Beige

1975 300D
Parts Car
78,000 Miles
Rustbucket
Also Colorado Beige

1984 190D 2.2 (Dad's)
156,000 miles
Champagne Metallic Clearcoat