"Race" Block

RammerJammer75 said
Browsing through Facebook marketplace for stuff I don't need, I came across a 318 the owner swears is a race block (casting number 4104230-318-4). Doing some research, several sites list it as a race block except for the site (mopar casting numbers) says it is a '76-'84 standard block. I wonder what the deal is. I also did read a similar post on FABO about these casting numbers and that one stated it was more than likely a standard block. I know the X on the front of the block is a dead giveaway but I'm still curious about your thoughts on the block and why there would be so much conflicting date on that specific casting number.

There is conflicting information because every time a question is asked about these old blocks tons posts talk about regular old 318 blocks.
The fact is when the old race blocks were cast they used an existing casting number. So the only real way to know for sure it is a race block is the other markings on the block itself.
If it has the large X or R on the front of the block it should be a real race block.
Check out post 76 in this thread for photos of real race X block with same casting number you posted, except it was a -5 casting instead of -4:
Mopar R1 block