I used to own an Avalanche before my 40th 370Z.. My Avalanche came with a tent that listed at $350 new back then... and can be found now for around $260. Its never been used - stored in the garage all this time. Has all the pieces.. If you are interested, I am looking to get $150 - plus whatever for shipping. I use UPS to pack and ship & this would probably be cheap. I'll go ahead and say I'll cover anything over $15 bucks if necessary for shipping. So $165 would do it.
Included below is a screen shot with the tent set up - and a UTube video for set up. I set it up once. It took about 10 mins.
Chevy Avalanche Truck Tent by Sportz Truck Tents
YouTube - Avalanche Tent set up