Need info on this block

Look at the pictures of the 1969 blocks below from 440 sorce . The drain plug in the block location? and the strengthening ribs?. The drain plug looks simular to the later cold weather industrial blocks. The last picture is of the industrial block it looks close but it is different.

First picture is a early block without the rib

Second stated on 69 model on E440 code

Third is the industrial cold weather block

blocknorib.jpg

blockrib.jpg

hdblock.jpg
The block above looks close but its not. There is no casting numbereither
40973.jpeg