just saw your post on v drive size i havent looked on the board for a while from my experience and what i have seen hallcraft is small like the one in my 1960 biesemyere loud but small straight cut gears
The smallest one I have seen to date is in the Blinger, and I'm almost positive it was made by the Grose's. It looks barely big enough to house the gears and bearings, and nothing more. Keep it tight, keep it light.