Hi,

I've found a 440 block that according to its casting #2536430-1 should be a 68 unless I am mistaken. I'm wondering what the second sequence of #s mean, can anyone enlighten me?

Good day

What does the 2nd number mean?

 

I think it's possible that production date of 1965 is plausible for the first 1966 model year cars to be manufactured even though the first 440cid production is known to be 1966 To my knowlage 2536430 is cast # to 440cid from 66 to72 , Adjacent #1 is probably first production serie . Second set of numbers is for production date 9 1 65 would be : september 1 1965