Peterbilt 379 transmission cooler

Fuller has a cooler kit that mounts on the bottom 6 bolts of the auxiliary section. About 250$ish

 

Some are air and others have a heat exchangers. Check with Peterbilt to find out your part number and how it mounts.

 

I would just get the air cooled and Mount it to the cross member just above the trans or behind. That’s how I’ve ran mine.

 

If its not getting hot I wouldn't worry too much.

 

Can you find out if the PO had a transmission cooler failure, (the looped coolant line)?
My '03 379 (avatar) had a cooler failure and mixed the trans oil with coolant and the radiator with oil.
ATOMIC mess. Ran it maybe 200 miles. After the mega cleanup I looped the cooler line and ran it that way for quite awhile and no problems.
That being said, I didn't run heavy or out west in the desert.

 

I just run a generic heavy duty truck type cooler and have it mounted to a cross member.
Unless running extreme conditions that will be fine.

 

I bought a reman trans that showed up on pallet, it had a pump. Called the builder as the old one had no pump or cooler. They asked what the truck did. SE regional truck. Said put plugs in the holes and run it. That worked fine.
Thank the loop hose or air cooler is a better idea.