I bypassed my factory cooler, if you've ever seen one, you'll know why, they're worthless. It's only a coil of tubing submerged in coolant in the radiator side tank. Cut the steel lines just before they bend upward to the radiator. Continue them forward and then go up, in front of the A/C condenser.

 

The main reason I didn't completely bypass the stock cooler is in the winter when the antifreeze warms up it'll also warm up the trans fluid. I know a properly working trans should work properly in -30, but a little help shouldn't hurt.
I really like the B&M Super Cooler 70255 with the exception of the crappy standard hose clamps. I replaced them with fuel injection line clamps (type with the nut n bolt).

 

That one is plate & fin design, same as my Hayden/Imperial. MUCH better heat transfer than tube & fin. The reason I bypassed the OE cooler is to keep hot trans fluid out of the radiator, and hot coolant away from the trans fluid. Keep it seperated, it's a win win situation: better cooling for the engine, better cooling for the trans, not really worried about creating heat in the winter.

 

This is really helpful. Thanks guys!

 

Yeah the stacked plate & fin is so much stronger too.
I read on Jegs the model I got was good for
B&M 70255 B&M SuperCooler Transmission Coolers
16,000 GVW
9,800 BTU
11'' x 5-3/4'' x 3/4''
Amazing for a cooler of that size. If I had looked more at the truck I could have gotten a model up with a lot more capacity.
B%26M+SuperCooler - JEGS High Performance
For a small amount of money more.

 

The Hayden/Imperial #243012 is 11" x 11 5/8" x 3/4". It fits perfect: one side mounts to the radiator support, and the other to the hood latch support bracket. Drill a couple 3/4" holes to get inside the air dam in front of the condenser. Piece of cake to install. Not sure how many BTU's but it says it's good for up to 30,000 lbs GVWR towing up to 10,000 lbs. $65 but you need more rubber line than what comes in the kit, and 4 of the fuel injection hose clamps, not the cheesy worm gear clamps. In the heat of Summer, 95F, trans fluid temp holds steady at 125F pulling 1,000 lbs trailer. It used to run 170F to 180F with the OE cooler. Before and after temps were on the scan tool, for what it's worth. The cooler it runs, the longer it will last.

 

Yup, they suck worse than a hooker with a chipped front tooth!
Sounds like a very decent prodict, more for the OP to think about. With the B&M I got I didn't have to cut lines though. Up to the OP with our postings.