Purchased a used 2001 Durango with 115,000 miles, 5.9 engine, auto, 3.55 gears.
I overheated the tranny pulling 3,000 pounds at 70mph in small mountains, and it has an aftermarket cooler. I slowed down to 55 mph, and it cooled off.

Question - Will changing the transmission fluid make it run cooler? Are there other problems that can be developing?

I was told not to change the tranny fluid, it may make the transmission go out. I really hear this about GM products, can this cause problems with Dodges also? Should I chance it and change the fluid anyway?

Next question, where is the best place to purchase ring & pinion gears and bearings for the rear end?

 

If the fluid is oxidized then yes changing the fluid filter will allow more stabilization for heat transfer. Yes change the fluid!


Second, I just bought my overhaul kit from Six States http://www.sixstates.com/products/products.jsp but be for warned, THIS IS A DIFFICULT TASK THAT REQUIRES THE CORRECT TOOLS AND MANUALS!

 

what you hear not to do is flush the transmission as this can somethimes cause problems on older units, just changing the fluid is fine and will help in the long run but DO NOT FLUSH the transmission

 

^ +1 ^