There is no box. Just the pinion and segment.
I had a Craftsman lawn tractor I bought in 1997 with the same set up. That steering gear didn't last long. As I recall the new replacement part was different somehow and it did outlast the rest of the tractor (the tractor was shot after 20 years).
I'm sure I didn't pull the engine. I think you probably need to pull the wheel, battery, battery tray and cowling around the steering shaft to get it out.