if your truck is not shifting right there is a little plug on the transmission case and you will have to look in that whole, there you will see that there is a gear in there and you have to rotate that until you see a set screw and that set screw will loosen or tighten the shifting arm that ingages the second gear. so what sonds like that problem is is that that set screw is too tight. if you have the manual for it it will tell you which way to turn the screw, if i am correct it should be counter clockwise. dont quote me on that but i think it is. just get the manual and read the instructions on there it will take a few times of trying and getting mad but it works.