Actually, I just checked my build sheet and I have "NHBP Auxiliary Transmission Oil Cooler".

The word "auxiliary" is kind of interesting since there is only one cooler and it doesn't pass through the radiator. The fin area is about 20 x 7 x 5/8".

 

My cooler is 20 x 7 x 5/8 as well.

 

While your at it, you can flush your tranny as well. Just unhook the return side of the cooler line and start up your truck with a large peice of cardboard and a pan underneath. When the fluid output slows down alot or starts spitting, turn your truck off and pour in 4qts. Do this 4 times and you'll be flushed. Just make sure you tranny is warm when you check the fluid level. On the 4th time, only add 2qts because the first time you would add 2qts too much to get things rolling. Hope you follow me? I'm pretty sure the return line is the further back of the 2 on the trans housing.

 

Rojhan, I called Dodge parts dept (not much help of course) and just asked for the Heavy Duty trans cooler for a 2005 1500 Hemi. He gave me part number 55056472AB at $189. He could not tell me anything else about the part. When I Googled that part number I got a pdf of Dodge parts lists. I'm attaching the picture of the part and description. This part looks exactly like what is on my truck. You said earlier in the thread that you have the tow package, so I'm thinking that the auxillary trans cooler is the same thing as the heavy duty trans cooler and I should be good to go.

 

That looks just like it.

 

More info. I found the official Dodge 05 1500 Ram options sheet which lists every option for the 1500's and this is cut and paste of the tow group: Notice, no transmission cooler.

Trailer Tow Group—includes Class IV hitch receiver, 7-pin wiring
harness and 750-amp battery (ST, SLT, Laramie)

 

55056472AB is an 8 row, 55056472AA is a 12 row, and 52029089AB is a 24 row trans cooler. I found a thread on another forum discussing that all these trans coolers are interchangeable.

This site list the 52029089AB cooler at $203 + shipping

http://www.trademotion.com/partlocat...&siteid=214666

 

Odd. Mine is 15 rows.

 

I have the towing package and my cooler measures 20" long x 7.5" tall. I regularly tow a 25' cruiser and I have yet to overheat the trans.

I do know that some guys who live in the northern climes have trouble with their trans not getting up to proper operating temps in the winter, when using the HD trans cooler.

 

It seems like the OP got his questions answered, due to a 2 week delay in posts. Rather than start a new thread, im just gonna thread jack

How would I know if I have a trans cooler already from the dealer? I know I dont have the tow package, because I had 3.55 gears (before the 4.56 changeover) and no 7-pin harness (only the 4-pin with class IV hitch). Oh, its an 03 QCSB Hemi.

Now for the scenario. I'll be moving in August to extreme North Dakota (with winters commonly -30 or -50 degrees). I'll be towing a trailer between 7-9k pounds with all my crap. I plan on buying a weight distribution system as well as a brake controller. I plan to also put in the trans temp gauge. Do I need a tranny cooler? Also, because I dont have tow/haul mode, should this trip be done in O/D off? with the 4.56 gears at 70mph i'm pullin some screamin rpms (3500ish i think). As for tires...are my 35" Pro-comp x-terriains gonna hate me for this? Thanks!