The 1980 has pencil glow plugs. The relay not sure which one is in there.

IDK if I was supposed to pull the NSS wiring harness from the 240D manual donor car. I can't seem to find it and I know it's not in the 300D. From memory I believe the car's auto trans NSS wire harness was toasty and fell apart as most do. Looks like it's hanging under the car right now - it's shot. I guess the mechanics bypassed the NSS altogether and perhaps this is causing my problem.

They did wire that switch on the clutch to be a clutch safety switch. Since there is no NSS tho I'm wondering if the car thinks it's in park and fires the glow plugs when driving because there is no NSS connected. As such I don't have back up lights either but that's an easy fix. I need to figure out why the glow plugs are firing when driving and how to cure this. I can go without the clutch safety for sure.