How do I adjust power steering gearbox? on 2001 Pontiac Firebird

I just changed rack and pinion assembly and the first couple days everything was perfect.. And just recently I've got a lot of play in steering wheel. Was told to tighten gearbox but not sure where it's located.

Asked by for the 2001 Pontiac Firebird
Rack and pinion is not adjustable! Reckeck the install or have it checked!!