The next type of Model 40 was the Model 40C. It had a bigger cabin so that four passengers could be carried. Model 40As had their engines changed to even lighter ones. Model 40As with this new engine were called the Model 40B-2. The Model 40B-4 was another model which had the cabin of the Model 40C and the engine of the Model 40B-2. Boeing Model 40s were made until February 1932.