I loooked them up on three popular sources and did see a pattern. The wire length was also a clue. Looking only at ones
Claiming to be Bosch. I found one with 320mm intake I believe, usually more expensive, and the 990mm exhaust. Plus the Bosch
universal 4 wire always described as premium waterproof, heated etc, although sometimes it was a little more.
Anyway the dealer wants $150-200 x 4, and I ordered with 20% off fathers day sale from car parts wholesale for $57-59
each minus 20%! so four cost less than a third as much.(less than 200 delivered)
We will see, but your comment is exactly what I wanted to know.
Is this site great or what?