Go to auto zone and get the $16 dayco tensioner pulley and replace that too. You're going to need a buddy and a 1/2" drive long rachet.
The routing is the exact same as the 3rd gen.
My best advise is to take the tension off the belt and slip the belt off of the alternator first.
You must install the rachet to the belt tensioner from the bottom and passenger side of the truck. The hardest part is slipping the belt through the gap to get it off/on the harmonic balancer.
The tensioner has to come off in order to get the belt off/on as well. It's a 13mm bolt head, use a 3/8" drive rachet and shallow socket, or ratcheting wrench, it's kind of tight in there.
2010 3500 DRW Big Horn CCLB Auto 4x4, leveled, Iron Cross HD steps, Mag-Hytec Trans Pan & Rear Cover, Cooper 285 ATP, 106k miles. Jayco 256 Eagle, Viking 700 EPS