o-ring

Can anyone tell me if the oil pressure sensor behind the intake near the firewall needs a o-ring? The part number is acdelco d1818a. It does not say in the description if it need the o-ring or not.........Thanks!

Hi Folks, Have a 2001 Tahoe Z71, with only 87K on it. On a trip up to Mt. Rainier the motor started making a "ticking" sound, and seemed to be there even after warm-up. It would go away, as well, here & there. But it easily made the 7 hour round-trip to the mountain & back. Now the noise is...