Trans bangs after being on the highway

After i spend more than about 20 mins on the highway and get off to drive around town,the transmission will bang hard from gear to gear until i stop and let it sit with the truck off for a few minutes. It will only do it if im going like 75 or faster or if i get stuck in NYC's famous stop and go traffic. I do a very high amount of highway driving goin from state to state weekly so i cant afford to get stuck in another state with a blown transmission. Any ideas?

i had that same problem i would go for a drive down the high way and once i got off the highway and accelerated it would bang into second gear violently i stuck a tranny cooler in line after it flows through the rad cooler and it has never once did it again! it seemed like crusin on the highway heated it up a bit then it would do it but this worked for me . If you dont have one on already wouldnt hurt to give it a try. Good luck

I agree with the above assessment.  I have experienced this same thing wiht quite a few other vehicles and had much the same experience after installing a cooler.  Hot transmission fliuid can cause all finds of odd problems.