Replacing the TCC solonoid
 

Can anyone give some advice or details on replacing the torque converter clutch solenoid on a 2004 C70? I have a code "P0740". The transmission shifts hard and slips in the city but locks up and does fine on the highway. I just got the Mobile ATF 3309 fluid and am going to change that first. Like to get some insight or the learning curve from someone that has done this. I am very mechanical and have all of the tools.
Thanks,
RAT