Sorry this is a little late guys.
From GM:
Solenoid PWM - P/N 24227792
Converter Clutch Solenoid - P/N 24234138
They both come up on RockAuto as well. There are 3 brands for the PWM, one of them being ACDelco. The converter clutch solenoid on RockAuto is ACDelco. I'm not positive what brand the stealership carries but I would assume ACDelco. Rockauto is 15-20 bucks cheaper on both of them.
When it was happening on my wife's truck it was distinctly coming from the transmission area. I thought it may be a diff/traction issue at first, but after duplicating it to try and pinpoint I realized there's no way it could have been. The surging was happening the same way wether I was going from a stop or cruising down the highway at 65. The diff would obviously be spinning faster at highway speeds would change the frequency of the slip so I ruled that out.
That being said, the best way I could explain the feeling is if I were in a truck with a manual trans and repeatedly pushed the clutch in and let it off. The TCC was just letting the power slip off and on until I hit the throttle or brake. I also noticed the surge more whent the trans was warmed up.
EDIT: It's been about 2 weeks since I replaced the parts and the issue has not repeated. OLYELR, I completely understand not wanting to throw parts at it. From my searches through the internet, Mitchell, and ALLData, I really didn't find much helpful info and decided to give it a shot. It was worth a shot to me since the oil/filter needed serviced anyway and I didn't feel like paying the dealship's rate to troubleshoot.
