LT-1 487 vs 487X Heads

[Chris Baird]

Anyone know what month GM cast numbers went from 3973487 to 487 "X"? I know it's around 1971 and 1972. My NCRS book says "later 1972" cars had 487X heads, and before I shell out the bucks I need to be sure.

Also, is NCRS judging casting numbers and dates for heads (you can see the driver's side casting # with oil cap off), or is it just the casting symbol on the front?

Thanks, Chris (NCRS 36056)

[Ed H.]

Re: LT-1 487 vs 487X Heads

Chris,
I cannot speak to the year of the head change, but I was judged at the Western Regional and the judges verified the heads by the marking on the front only. You are not required to pull your rocker covers off.

[Ed H.]

Re: LT-1 487 vs 487X Heads

Chris,
I cannot speak to the year of the head change, but I was judged at the Western Regional and the judges verified the heads by the marking on the front only. You are not required to pull your rocker covers off.