I had my 53 block replaced with another complete motor. I know where the 53 was stamped but where should I look on this one. There is a stamp on the front that says made in Mexico. Does this mean it's a 55?

Nope, its a Mexican Block and stronger than the Tupy blocks.

53 is normally found near the turbo oil return line...

http://stamey.info/Truck/Cummins53BlockFAQ.htm

Sorry for any confusion. I know where the 53 is, I was wondering where to look on the new engine block (made in Mexico).

should be about the same spot on the block..

Here.

per Tapatalk on my EVO

My block has no markings in that area, or any other either. Where did you see the "made in mexico" at?

It was stenciled on the front of the block.