Special T has them on this page for $0.40
http://www.specialtauto.com/delorean...ne-tuneup.html
From what I gathered from an old delorean wiki they said that this part works:
http://www.pepboys.com/product/details/8328861/00202
So, that makes it a M16.4 (aparently also called a M16x20mm)
They look to be common enough. amazon has this, but what is up with the $5.99 shipping
http://www.amazon.com/Metric-Non-Asb.../dp/B00HER9UGM
Has anyone has found a new plug to swap it too that has a captive neoprene 0 ring now? I see special T has a new one with a 17mm head, but I'd much rather have a tiny 10mm head so if I ever do have it in a shop they will not destroy my pan. Like this attached image on one from a chevy cruise.