A prototypical 3M division will be roughly:
1 Division President
3 - 6 Vice Presidents as division functional heads (marketing, sales, laboratory, manufacturing, etc.)
15 - 40 Directors (portfolio functional leaders, area division leaders, lawyers, division/corporate scientists)
The above group of people for a single division will usually fit in one very large conference room.
3M is roughly 20 divisions, there should be around 500 division directors in the company. BUT...
Manufacturing probably adds another 300 or so as many plant managers now hold director titles.
Corporate overhead probably is also 300.
All said and told, I would estimate there are around 1,100 people, perhaps a bit more, at 3M with director or sr. director rank under the new title structure.
Reposted from @zkf+1jGgI7IF for info.