[PhillipAbbott79]

Originally Posted by trdcrdkid

T206resource.com has checklists for all the different backs, here:

http://t206resource.com/Checklist%20Main.html

No back brand has all the fronts, but I think Piedmont (factory 25) comes closes, if you combine the 150, 350, and 460 varieties. Ted Z would know about this, since I believe he has an all-Piedmont set. To answer your specific question, there are only 156 different fronts with Piedmont 150 Factory 25 backs:

http://t206resource.com/Piedmont%20150%20Checklist.html

The Plank and Wagner in piedmont 150 were unissued, bringing that down to 154. They are scraps.