Technical 1949 mercury flathead trans

I'm wanting to retain my original rebuilt flathead motor with a late model AOD transmission, any suggestions appreciated? I understand an adapter will be needed, however which (Ford or GM) will be the best fitment, altering trans mount and drive shaft not a problem, but I do not want to tunnel or alter firewall.
Tom

 

I've only seen adapter kits for the C-4 trans, not the AOD. AOD is larger than the C-4 and t******* of the tunnel will be needed.

 

Check wilcap adapters.

 

Speedway, Wilcap, and Bendstens all sell adaptors to put an AOD (or C4, they have the same bellhousing pattern - i.e. the Ford Windsor pattern - 289's, 300's, 302's, 351W's, etc) behind your flathead. Whether or not the AOD will fit in your tunnel is a question for someone who has done the swap, and I am sure there are more then a few on this board as a flathead powered '49 Merc is a fairly popular car.

 

I think regardless of which ever automatic you use will require modification to the hump because they didn't have automatics til 51. I believe that the 51's humps are larger than 49 & 50's to accommodate the automatics.

 

thanks for your feedback