Leatherseats.com has them as well with an instructional video. The factory also has a heated seat kit the parts department can find and pulling them from another vehicle is almost like cheating when you find a cream puff set.
Just be aware that if you find front seats from a 07-10 Esky and 09-10 Tahoe, Yuke or Burb that have the a/c seat feature they are a logistical nightmare to get working. Both seat heating & cooling are based off an actual two way heat/cool unit that is connected to the trucks BCM.
All other 07-10 Tahoe, Yuke, Burb seats with heat only are compatible because they have standard resistance heated mats inside.
The kicker is the 11-14 Esky, Tahoe, Yuke & Burb seats that are not cooled, but vented with air from the cabin. They can be used as there’s only a fan inside and standard heated mats too.
Happy hunting