Even a blind squirrel finds a nut once in a while...
The model is a GTA5523BNS.
Lucky for you, it should have a billet compressor wheel. That wheel is somewhat smaller than the aftermarket GT55 (133mm). Max flow is ~132 lb/min. It will make 50 psi/PR 4.4 with ease (at slightly less than max flow of course) and probably more if you push it off the map.
You may want to check this: sometimes the "A" after the GT can imply that it's a boreless compressor wheel. If so you will not have a separate nut holding the comp wheel on, it will be all one unit that screws onto what some folks refer to as a "stub shaft" instead of a full length normal shaft. If so, you won't be able to put another wheel on it, you're stuck with it (unless you replace the entire turbine wheel/shaft assembly). This is done to give the wheel a lot of fatigue resistance in situations where the engine idles a lot then goes full throttle and then back to idle. They say garbage trucks are some of the most punishing environments for fatigue for this exact reason.
Turbine wheel is the high-flowing aero that is the same as the GT55 aftermarket/performance units, 84 trim, 111mm inducer. The 1.18 housing will max out at ~63 lb/min (agrees with what you see on the Garrett website) with very good efficiency.
And, obviously, you have the divided volute housing that's internally gated. I believe on the aftermarket GT55 you get open volutes and no WG. But I would bet you could fit the aftermarket turbine housings on it if you wanted to gain a little more efficiency and top end flow.
Hope that helps. Nice find!