You made me curious enough to get out my dial calipers (metric, of course) this morning, Matt. Are you ready for this?
The nut on my T30HGc actually measures 44.8 mm which is a bit more than 1.76". I suspect that the quoted 1.73" is a nominal minimum size...I also suspect that Gregg, and the folks at Elderly, actually measured one!
You're welcome. Now go spend some money...
Phil