COPO 3963512 block. No VIN#

[Tracker1]

Chris,

Your block was cast the last day of August 1969 - that means it was prepped for a 1970 model year car. It's assembly date is September 8th (0908) - again 1969. 512 blocks were not just used for 427s. My LS6 454 and LS5 454 both have 512 blocks cast in late 1969.

I can assure you that the gentlemen who have responded to your query in the above posts are "sure". They are some of the many knowledgeable people you will find on this site. Take their opinion to the bank - and enjoy your 454.