It's a glow plug or three, they've never been changed, I can see all 8 from the top, nat asp, I got an over the phone quote of 500$ to change them, that seemed a tad high. 100$ for some OEM plugs, 120 labor and 100 for what ever. Is there something that I don't understand, looks straight forward, 10mm deep well and antiseaze, am I missing something?