ok search 4l30-e shift solenoid on ebay motors look at the kit,has 4 solenoids.
after you get em.
take tranny pan and filter down.
you will see the valve body
follow the wiring harness to the 3 solenoids
at the front are to side by side a and b
do one at a time take the connector off be careful not to break the clip.
there will be a dowel pin to the left of each solenoid grab it with some pliers and pull it out then pry the solenoid out it will be kinda snug
put the new one in,push it in all the way if it is out too far you will never get the pin back in.
the other two are basically the same procedure
put the filter and pan back on fill it up with dextron lll and you are done
hope that helps
cheerz