Block Casting Imformation

KP said
Can someone please tell me what year blocks these are along with what would be the best of the three to hold onto?

4006630-440-10

6556430-7

36988830-440-6

4006630-440 is a 1975 through 1979 block.

36988830-440 has one too many 8s in it and it is a 1973 and 1974 block.

6556430-7 I show nothing on.

How about 2536430 and it shows to be 1966 through 1972.

The other numbers after the 440 are the tooling revison numbers.

The older 2526430 if that is what you have would be the higher compression engine from the factory.