This only works if you have an automatic transmission. If you pull the flex plate inspection cover, and look between the flex plate and the rear of the block, there is an external counter weight on the crankshaft. If you look carfully, you can see the thin casting serparation on the weight if the crank is cast. I don't know what it will look like for a forged crank, though. Next time you're in a junk yard looking for a forged crank, you don't have to pull the entire oil pan, just the inspection cover.