Diagnose Oil Leak on Toyota Pickup

What happens here

Upon entering his large metal workshop, the 'Mega Shop', the creator immediately turns his attention to a persistent oil leak on his 1988 Toyota pickup truck, known as the 'Yotacorn'. He drives the truck onto a four-post lift (a Tuxedo Lift from Northern Tool and Equipment) to gain better access to the vehicle's underside. A significant puddle of oil is visible on the lift's platform, indicating a substantial leak. Before attempting to fix the leak, he checks the engine oil level using the dipstick, confirming it is full, likely from a recent oil change. He briefly starts the engine to circulate the oil, after which he will perform a more detailed inspection.

Goal: Identify the source of the oil leak on the 1988 Toyota pickup.