It's the center bolt on the zoomed-in pic above, in between the two fittings, on the top of the coolant intake part of the front of the engine. I thought it was another fitting port or something.

-Ryan
1996 Dodge Ram 3500 dually diesel 5spd

 

Purging the air out of the cooling system.

 

NOPE!! that is a head bolt. you can tell by the grade 12.9 on the head of the bolt, and also the 90* > which is the torque + angle when tightening the bolt. DO NOT take it out unless you are removing the head.

 

Yep, head bolt, visible due to the separate head covers on the 12V- do not touch unless you have a cause and you know what you do. (torque to yield bolt, measure stretch before reinstall.)