I got the tensioner for like $60 at schuck's/O'reilly's. Just make sure you have a decent sized breaker bar or ratchet for the tensioner. I didnt remove the fan shroud from my truck and it took me like 20 mins to change the belt, tensioner, and idler pulley. I dont know how much different the LBZ is, but on a LB7 it is simple.
2016 GMC Sierra 2500HD Denali
Extang Blackmax Tonneau
Weathertech floor mats and mud flaps
X-pel clear bra
295/60-20 Toyo Open Country A/T II
SOLD 2004 GMC Sierra LB7