I have read through several decoder websites and even a 600+ page GM manual trying to figure this one out. I recently got this engine from a friend while helping clear out his father in law's place after he passed away.

It is a straight 6. Serial number on tab just behind distributor. It is reasonably clear and appears to be F6T2HE. Maybe HF? The block casting code isn't as clear, but appears to be 3887004.

Looking for any clue as to what year the engine is and what it came out of. I'll try to upload some pictures.

Serial number