With 140k hiway miles on my truck and a good bit of towing a 14' trailer should I be changing my transmission fluid anytime soon and what is the best product to put in? Thank you in advance

Nah, you don't want to run it dry.i read a post saying that if you drain the pan and then pour in 2 quarts thru the dipstick hole and run the truck for 10 seconds and turn it off, drain the pan again and repeat this for 4 quarts it will flush for you. Does that make sense to you?