Mystery Motor SBC?

[econo racer]

The block has the numbers 397004. Should be another number behind the 4. #3970014 and 3970010 are common. Never seen a 6 digit like this. 99 % sure it is a 350-also has 2 bolt mains 2 piece seal. Whats up with this

[1980RS]

Maybe they forgot to use the 1 digit in the casting so more might be out there.

[econo racer]

Might be a collectors item or rare special block making it worth an additional $50 Any Target Masters have these type of numbers.

[tenxal]

Garden variety early-mid '70's 350 passenger car.

[econo racer]

I checked the number over on Mortec and nothing.

[BillK]

In the last 30 years I have seen plenty of blocks and heads from multiple manufactures that had messed up casting numbers. Usually a number missing like yours has. When you cast a million blocks there will be mistakes sometimes. Look on the pad up on the front of the deck and see what numbers are stamped in it. That will tell you what the block was when first installed in a vehicle.

https://nastyz28.com/spmenu.html

I would not spend any more trying to solve a mystery that really is not one, just a mistake.