74k20

So I have searched and searched but I cannot figure this one out. I have 2 knock sensor that I found in the junkyard and am considering for my 383 tbi setup. The part numbers are dr699 4027 and dr699 4158. I forgot to figure out if the donor vehicles had a 305 or 350. Does anyone recognize those part numbers? I can't seem to find any cross references to figure out what application they are.

Also, the rubber material that is around the plastic connector is very cracked/half missing. Is this sure indicator of a bad sensor?

Thanks for the help.