Radiator question

[bearhead]

99 gmc sierra, 5.3. 4x4. I replaced my top hose due to it exploding, as I replaced it I noticed on the driver side 2 "threaded silver holes" along the radiator. It was still hot so I didn't go digging around to see if they are actually holes. Soo. Are they? Am I missing something on my radiator?

[muddkatt]

Are they on the drivers side? Could be for the transmission cooler that is built into the radiator.

[bearhead]

I have a 99 gmc sierra 1500, 4x4 with a 5.3  SLT.   I'm getting it ready for a cross country move, I am about to do a radiator flush today when i noticed I have two holes on the backside of the radiator, both on the diver side. One is right below the BIG hose. The other hole is near the bottom. The was or is obviously something suppose to be there. cause i can see the inner webbings of the radiotar and there are threads.  ive never noticed anything leaking or temp sky rocket on the truck.

[bearhead]

driver side

[txab]

Trans cooler should be on passenger side. Ports are probably for the engine oil cooler option

[Chebbyfan]

Probly oil cooler, I'm guessing.

[Logan Lanfear]

I would agree with the oil cooler. 

Part of the max towing package. 

Surprising they use the same rad just with no lines.  

[bearhead]

so do i need to plug these holes? i can see into the radiator.

[Mr. Z71]

With the truck being a '99, I think it's pretty safe to say the radiator has probably been replaced at some point in time and the exact factory replacement radiator was not used. The one that was installed was probably for a truck with the optional oil cooler. What you are seeing is not the inside of the actual radiator where the coolant resides but is the insides of the oil cooler assembly which is inside the radiator tank. It is not necessary to plug the holes as the oil cooler is not being used.