Update: I sent the TB28 back to the seller and they got a new "GT2860" to my door a mere 3 weeks later.

I measured the wheels, but the camera's battery was dead. I will have some pics tonight.

Comp Wheel: Ind - 54mm / Exd - 76mm
Turbine Wheel: 52.5 mm .64 A/R

That looks quite a bit more like a 2876 to me...