Mart got it right. Here's some photos of the engine block with the "bell housing" cast as part of the block.
https://www.bing.com/search?q=1940+f...ANAB01&PC=HCTS
The later blocks were known as 8BA style blocks and used a separate bellhousing bolted to the rear of the block to house the flywheel. Early Ford and late Ford flywheels are not interchangeable.