Did you do the work yourself? If so was it difficult.One of the first changes I made after buying my 2008 LT3 with 126k miles was replacing all four (4) shocks with KYB Gas-A-Just units. Had a great result on a prior heavy full-size vehicle (2004 Crown Victoria LX Sport) with them and figured I'd go this route again.
Great results with the Tahoe: good control combined with comfortable compliance.
Here's links to Amazon listings for front struts and rear shocks:
https://www.amazon.com/KYB-555054-Gas-a-Just-Gas-Shock/dp/B003WE22EI/ref=sr_1_9?s=automotive&ie=UTF8&qid=1492297129&vehicle=2008-47-499-430--9-6-8-8149--1-1-145-104-1-0&sr=1-9&ymm=2008:chevrolet:tahoe
https://www.amazon.com/KYB-551121-G...rd_wg=DXMVJ&psc=1&refRID=321JXMAT3QEKG81Q7Y5N