How do you tell a 350 4 bolt engine with engine numbers?

To identify a 350 cubic inch engine with a 4-bolt main, you can look at the engine block's casting numbers, typically found on the driver's side rear of the engine, near the bellhousing. The casting number will indicate the engine's displacement and production year. Additionally, you can check for a stamped engine code on the front of the block, which often includes a letter and number sequence to verify the engine's specifications. A 4-bolt main engine typically has four bolts securing the main cap to the block, which is a distinguishing feature compared to 2-bolt mains.