I currently own a 1971 Chevelle SS with a vin of 136371R41830. Car came w/ a correct 1970 LS6 motor installed. Was wondering if the car could have received a 1970 motor left over at the assembly plant in Arlington, TX? Car has a Turbo 400 with a 12 bolt posi w/3.73 gears. Any help?

You do not provide any information to give you a answer.

What are the engine/VIN codes stamped on the front block pad at right (pass) head. What are the date codes on the block, head, intake etc?

What are the last 6 digits of the cars vin? Do they match the CON VIN on front of block? If they do not, its not the correct engine.

How do you know its a leftover 70 motor?