2 x 4 Earlier, without Cross Supports - have unique number on each brick in the anti-studs

GreenFox

I have 3 older red 2x4 bricks without cross supports. The 3 bricks have unique numbers inside each of the anti-studs. (Pics attached)
184
890
210
I searched the forum to see if I could find an previous discussion and did not.

Are these bricks special for some reason?
Are they ok to list in the 2x4 without cross supports?

Thanks in advance for any help you can provide.

Calibrick

These older bricks have their own catalog entry: https://www.brickowl.com/catalog/lego-brick-2-x-4-earlier-without-cross-supports-3001. These simply predated the modern ones. :-)

Jay37

Yes, they date from the mid-70s and the numbers refer to production molds.

More info here:

https://www.flickr.com/photos/111441268@N03/21779534870/

GreenFox

Thanks Cali & Jay!