Dodge: dodge transmision, dodge transmision, dodge truck

Question
I have a 1996 dodge truck 3500 the transmission is having trouble shifting when i start going it shifts good the first time at about 20mph then will not shift till 55mph or 2500rpms then shift good into 3rd and overdrive with no slipping .I tried transmission treatment changing filter and transmission oil carquest atf+3 oil I even changed the 2 cylinoids in bottom of transmission. Oh yea it has a cummings motor if it matters. I pull a 4 horse trailer a lot a matter of fact it starting going bad when I was pulling it.  I changed the torque converter about 2 years ago because it was shuttering bad. I rarely take it out of overdrive for at 60 65 its at 2100 to 2200rpms and it has 270000 miles on motor and runs like brand new. I'm lost please help.  I don't want to rebuild it if I can, but if I have to I will .
 Jim


Answer
Jim,
I have a Ram 1500 v-8.It started hesitating shifting.I talked to a friend of mine that owns a parts store,he told me to try something called TransTune made by SeaFoam.I was skeptical but bought the can and added it to my transmission and drove it up the road to get it circulating and noticed that the transmission was shifting like a new one.Try this and see if it works.Read the instructions on the can.The good thing about this is it can be added to your existing transmission fluid.You probably have a sticking valve body like mine was doing.If it can be fixed i guarantee you this will do it.Let me know how it does.
Thanks RamMan