Not normal Troy Bilt

I have a Troy-Bilt/Briggs Stratton 3250/3500 generator – model # 030378 Serial # 1015494054. I believe the engine is a B&S Series 900, but the only visible markings (without removing engine from the frame) is a sticker affixed to the underside of the engine. The sticker has two barcodes. The top one looks similar to a 12-digit UPC: 1210120116B8 - (Notice a B not a 3 nor an 8)
The lower is 13 digits:  0711918813216
This is not a normal 030378 as it does not have the normal air filter. Instead, it has some sort of a plastic plenum (intake resonator?) attached to the carburetor. This looks to be Briggs manufacture part  - It has the crank case vent, but I am not sure about this.  I would like to identify the specific engine as the plastic choke arm is broken off behind this plenum and is a bit hard to reach – I found especially so on cold, dark, snowy nights.
This generator is only used for power outages. If this ‘plenum’ is not supposed to be there should I find parts to go back to normal or go by the “If it aint broke don’t fix it”.
So, help on engine ID and/or how fix choke arm along with filter suggestions.  Will see if I can attach photo.