Hard shift high to low range

[Mr Hagg]

If the truck was to be in our shop i would first listen to it going into high and low. You can tell it the air pressure is not good as it will drag somewhat.
If it does drag I would remove the 4 bolts in the rear of the upper back bock where the piston it for the shift range (upper one) you can buy a kit that has the piston oring and other orings and gaskets needed. I find many times the barrel where the piston slides will be rusty from moisture in the system. I take cleaner and some fine sand paper and clean it up..INstall the new o'rings and you are good to go..

If it sounds like its got good air pressure and is working good but only slams when going down the road Id pull the back back and look at syncro. Many times when these go back it will slam ALL the time not just every now and then... It will also have a grinding sound of noise to it when it does it.. Many times the failure of this is because drivers flip the range on the shift to soon before they come to a stop. You will know its not right cause you will hear the transmission speed up and make a wining sound.

So with out checking into it further it really is hard to be able to tell you for sure..