Have you been searching anywhere before? What contacts do you have? where do you want to search? There is 100's of contacts to be taken all over and you can find parts where you least expect it.
You have clubs in Finland, Sweden, Latvia, Poland, Czechia, Germany, Denmark, Holland, Belgium, France plus more and the rest of the world. And suppliers of repro parts in many countries that also might have a lead for a crankcase half. And there's Ebay.
There is a couple of Yahoo mailing lists where you can ask.
101scout@yahoogroups.com
virtualindian@yahoogroups.com
1920sindianchiefmotorcycles@yahoogroups.com
For the different suppliers, best is to write and ask as keeping up with pictures on their homesites is a lot of work and mostly is a work trailing behind if it ever is done.
You can ask Randy Zorn: randy@indianmotorcycleparts.com
http://www.antiquebike.se/en/
http://www.indianworkshop.com/index2.htm
http://vintagecyclebay.com/catalog.asp?catid=147
And there's the Facebook
https://www.facebook.com/groups/893563860685798/?ref=browser
https://www.facebook.com/groups/766466093420426/?ref=browser
https://www.facebook.com/groups/527934510616397/?ref=browser
https://www.facebook.com/groups/893563860685798/?ref=browser
https://www.facebook.com/groups/209034145924398/?ref=browser
https://www.facebook.com/groups/1532780733647586/?ref=browser
