I have a 2002 Tahoe ls 5.3 4x4 with 225k on it. It seems to shift okay but There is a clunk everytime i shift from park to drive, or when i give it gas when starting out initially. (U joints are tight, possible rear end?) but what scares me is the check engine light is on for shift solenoid? and brake light circuit? There is a whine about 40mph, seems to be there when on the throttle and goes away when you let off. I can give you the exact codes later not in front of the scanner at the moment.. (Half of the third brakelight is out) the transmission fluid is pink like as it should be..any ideas? I'm mechanically inclined but auto transmissions aren't something I'm familure with.. Please help!

 

Welcome to the forum... going to move your post from the general tech area to the Tahoe Suburban area for more exposure..
That clunk is likely the slip yoke/spline shaft needing grease, its the portion of the drive shaft that goes into the rear of the transmission..

 

I 2nd the slip yoke as possible cause.

either grease or replace.

I dislike slip yokes. One of the first things to scrap in the Jeep world. (Rubicon doesn't use a slip yoke )