Transmission problems ?

Hello I have 98 chevrolet c1500. I really don't know what type of transmission it is I know it has a 4 on the first number, about a week ago my transmission stopped shifting to 3rd gear, we asked around and they told us to change the transmission control sineloid so we did we changed the 1-2 solenoid and 2-3 solenoid and new oil and filter, and nothing still won't get out of second gear is their something else to change before I drop the transmission down. Thanks