HEY FELLA'S, I'M A FIRST GEN OWNER ( transplanted 91 12-v into 1985 D-350 crew cab ) AND I AM IN THE PROCESS OF ENGINE UPGRADE'S AND TRANS. I HAVE AN A-518 ( NON - LOCKUP ) OVERDRIVE AND WAS LOOKING TO GET SUGGESTION OR EXPERIENCE WITH AFTERMARKET TRANS COOLER WITH ELECTRIC FAN. I KNOW DODGE OFFERED THIS AS AN ACCESORY I BELIEVE FOR D-350 92/93 MODELS AND WAS MOUNTED UNDER BED BETWEEN CROSS MEMBERS OF BED. WHAT ARE SOME OF YOUR THOUGHTS FOR AFTERMARKET COOLER? I TOW A 25 ft. SPORTSMEN WITH REAR SLIDE BEDROOM THAT WEIGHS APPROX. 6,000 / 6500#'S. THAT IS THE EXTENT OF MY TOWING. - KEEP ON RV'N - THANKS AUGIE DOG

 

Mite be wise to hook up a Tranmission temp gauge to see if a extra cooler is needed

My trailer is large and heavy when loaded 18000 GVW on the trailer so far my trans temp is ok it gets hot on steep grades but I back outta the throttle when its hot.....backing up can overheat a transmission quickly.....so a gauge helps you know whats happening with your transmission

 

I have a BD and it seems to work well, sounds a lot like what your talking about. It's mounted under the bed edge drivers side, has a fan that is controlled by a thermostat. The original owner put it on so I can't give you a comparison between before and after although I haven't seen trans temps over 200 (hot day towing 10,000lb long 6% grade OD lock out temp spiked after I exited at the top and slowed down) it comes on about 140-150

 

With the truck in my sig I tow a 5ver at max of 13k. The only time I have had overheat is backing with lots of maneuvers and once on the grapevine grade when it was being repaired and we had lots of stop and go preventing air from going through the stock cooler up front. I just installed a Derale 9" fan on the front of the stock cooler with a manual switch at my switch panel through a relay under hood. I just watch temps in the situations mentioned and flip it on when it gets over 180 or so. Keeps air flowing over the cooler. Tight fit but I made it work with a little grinding on the inside of the grill that can't be seen from outside.