Rockauto offers several knock sensors for the 350 V-8.
Airtech/Wells, Standard, Delphi and AC/Delco, also economical and standard versions.
What sensor to go for on a stock engine..?

 

AC Delco first followed by the Delphi.

RBob.

 

AC Delco = Delphi

https://en.wikipedia.org/wiki/Delco_...reorganization

Worse yet, all the mfrs buy from each other and re-box.

Any of the ones you mentioned are largely equivalent. I would add other OEM mfrs to the list as well; European such as Bosch and the Japanese such as Denso for example.

 

So if I buy the economic $15,60 Airtech/Wells, I'll get the same as the standard replacement $35,79 ACDelco?

 

Hard to say... it's entirely possible that what's in the box is identical, and made by yet another company.

Best to pay less attention to the printing on the box and more to the part that's inside it. Country of origin for example; look for other marks such as a logo or part # on the part itself; and so forth.

I needed a steering part one time recently. I went to my local NAPA store and found that they had 2, a 1-yr guarantee one for like $70 and a lifetime guarantee one for $100 or something. I pulled them out of the 2 differently branded boxes and looked at them. Turned out, both were the same Dana part, with the Dana logo and the same part number cast right into them. (which of course, Dana is one of those "reliable" type of replacement part brands, rather like AC Delco; they supply to the OEMs) I also checked at AutoZone: they only had their one "house" brand in stock, which when I pulled that one out of ITS box, I found .... you guessed it ... the same Dana part, identical in every way. Needless to say, I bought it however it came the cheapest.

Don't be too surprised if the knock sensor works the same way.

 

I ordered the Delphi sensor, as it is probably be the same as ACDelco.

 

Should do the trick.

 

I changed the coolant in my car today, and the knocksensor has to come out as it is a drainplug as well.
I noticed it was looking rather bad, so that's why I need a spare one, although the original sensor is still working right now.