Ted, when you had your suspicion about that sensor, I looked it up, saw it was a 4-wire and suggested it might work if it was just wired properly. You confirmed it was a zirconia sensor (as we generally see NTK on the board for the Regina titania sensors) so if only the ground wire was grounded, you'd be all set.

But I also understand it is nice to put in the right part so the next tech isn't scratching his head when he gets the car. I think you'd agree with that, but I just don't understand why your friend did not mention the reason for his choice of that part, opting to give up on the car instead.

I replaced one in my 89 two weeks ago, on the road out in the Midwest, and convincing the Advance Auto clerk to sell me a 4-wire Bosch universal for a car that wasn't listed for it, wasn't a smooth task. I prefer the 4-wire, because it does not depend on all the rust-prone exhaust parts to get its ground from the cylinder head. Also, it helped that I got lucky and found some on ebay 12 years ago, listed erroneously as "Volvo spark plugs."

NTK uses different wire colors, apparently, according to the cheat sheet that came with the Bosch 15730 I chose. The Bosch also comes with a sweet waterproof splice box.
--
Art Benstein near Baltimore

What engineers say and what they mean by it:
"Developed after years of intensive research"
It was discovered by accident.