Transmission line routing

I am researching transmission coolers since I tow a 6,000 lb travel trailer in the hot Florida weather.  Just curious how the lines route to the radiator. 

Is the bottom line to the radiator coming from the transmission and the top line from the radiator the return line?

Considering the Hayden 679 and looking at B&M and other options.  The OEM unit from GM seems on the small side for towing a travel trailer.

CenFL Avalanche said:

....   The OEM unit from GM seems on the small side for towing a travel trailer.

Click to expand...

My EXT has the LQ9 6.0 HO engine, full time all wheel drive with 3.73 gearing and I tow my 25' party barge with a dual axle trailer and all of our gear, for a combined weight of 5,000 lbs. and gosh awful wind resistance, during the hot summers here in Arkansas every year.

My transmission temp runs right at 90 degrees above the outside air temp all year round when not towing.

When towing in the heat of summer at highway speeds with the a/c running, I have seen the transmission temp as high as 205 or so.

That is a tad higher than in the same conditions and not towing.

While better performance might be had with a larger aftermarket cooler, I find that the factory unit does an outstanding job on it's own.

In other words, I do not see any reason for me to swap out the factory unit for an aftermarket unit.

However, if someone does not have an aux cooler at all, I would highly recommend them installing one, even if they do not tow at all.

If I had to tow in the mountains, I might think differently, but my towing is done mostly on flat lands and what most would consider hilly terrain, not mountainous.

I am in Florida hilly terrain.  And the trans temp on my non aux. cooler 2007 Avy Z71 has been over 210 in the summer.  After some research, I will probably go with the Derale 13403 or the Hayden 679.  The Derale unit seems like it would fit nicely on top of the horizontal support brace in front of the condenser coil. 

I would imagine either would be a good choice.

Post up your temps after the installation for others to reference.