The 37-40 bell housings were basically the same. The clutch fork ball was mounted further away from the tranmission hole on the 37-40. On the 41-46, the clutch fork ball was mounted closer to the center of the bellhousing. So even though both pedals mounted to the same three holes on the bell housings, and the clutch and brake pedal bracket are the same for all years, the set up is slightly different in the geometry of the pedal travel, especially the brake pedal. In other words, the 37-40 used a different clutch fork. Consequently, the 41-46 adapter made by Steve@Buffalo is not exactly correct for the 37-40, but I'm not sure Steve is aware of that. The adapter plate he sent me was a 41-46 adapter, but I made it work for my 37 by filing the hole out so it was larger and closer to the center of the adapter transmission hole.
I would say, if you use the 41-46 TRUCK bell housing adapter plate from Steve@Buffalo, you will be on the right track. To ease you mind, a short conversation with Steve would be a good idea.
Good luck!
Joe
