For anyone buying these that after receiving that you verify that they are TRUE Delphi units. The originals had Delphi embossed on the top and these show they're laser etched on the interior metal along with the part number. That could have been a change by Delphi but maybe not. Delphi has changed hands since so it's possible.
And the listing says "Brand: AD Auto Parts". Looking at their other listings, they seem to specialize in ignition parts for multiple car makers.
There were a couple of negative reviews, including one that said they failed within a year. Sounds like the Chinese clones.
While I appreciate the time and thoughtfulness that @mrrsm displays in bringing potential bargains to the community I must say I have never bought the logic of replacing 6 items, at a much greater cost, when only 1 has failed.
I often see the argument that they are all the same age but hell, my teeth are all the same age but I'm not going to root canal them all if only 1 needs the treatment !
I currently have 4 of my original coils from 2001 and 2 non-Delphi replacements. Given the state of current aftermarket or even "OEM" labeled replacement coils quality I think I would rather grab some original coils from a Upull yard to have on hand in the truck as a spare.
NP Gents... Just know that I was more interested in the Historical Importance of the Delphi Brand as per our GMT360 History along with presenting the images of these OEM COPs "Strictly for The Purists" among us... and so the Title of this Post is of course, Self Explanatory.
But as Tom (@TJBaker57) points out... Regardless of whether you are replacing COP(s) with NEW or USED Coil Over Plug Unit(s) as needed... It makes perfect sense to "Verify WHY ...BEFORE You BUY...." and only replace the Damaged COPs . This On-Topic Training Video on "How To Test COPs using Many Different Methods" is very much worth a look or two:
NOTE: Testing COPs "In Situ" allows for the Stress of Compression and the Fuel to Air Ratios delivered to each Cylinder provides a more realistic circumstance of having High Atmospheric Pressure working to defeat the Spark Events. ONLY an Oscilloscope is capable to performing this Diagnostic and with the use of a Paddle or Coin Sensor... it becomes very straightforward. Static Bench Tests of COPs and Spark Plugs will only get you so far!
The Attached Images are of a "Known GOOD COP Wave Form" well explained for Novice Oscilloscope Techs the DIFFERENCES between what is happening of the Primary Side "Charging" side of the COPs and What is happening on the Secondary Side of the "Fire" making areas of the COPs:
Divide your Spark Voltage in HALF with a Black Line to see Which side of the COP is suffering problems!
That takes me back to high school auto shop class in the early mid 70s and our Sun "Engine Performance Tester" with all the bells and whistles. That auto shop had everything, even a machine to match the radius of your new brake shoes to the measured diameter of your newly turned drums!!
When I ran shops we had a SUN battery load tester, that we rolled up to the vehicle to use. Now the same thing is done with hand held equipment. Had those SUN Engine Performance Center's too. I mainly used the exhaust sniffer of that machine to check for exhaust fumes in the coolant at the radiator. Found lots of failing head gaskets doing that.