Somehow never noticed this until a couple days ago but it looks like my 5T has a big patch behind the injection pump. Is this not supposed to be here? Maybe it had weak coolant and heaved the block at one point? There are small screws all the way around the plate. Havent noticed any leakage.

Thats very interesting because my 5t has almost the exact same patch. I asked the question of the forum before and the freeze repair seemed most likely. I wonder if there was a casting flaw on that run of blocks. Maybe since the repair is so close it was a cat directive, or I could be that it was just the obvious thing to do.
Interested to see if anyone else has this repair.
Oh and good eye, it took me over a year to spot the one on mine.

maybe that patch is an intentional part of the design...and has some other purpose?

- a burst panel in case of coolant (water) freezing...
-easier access to coolant passage(s).. for....??
-i have no idea...

I wonder if it shows up on the parts diagram??

That's typical of where freeze damage shows up. Apparently the block castings are thin in that area.

No kidding! Very interesting Scott. It looks identical to mine. There must have been something going on with Caterpillar. Too consistent to be a home made jobby. I looked in my parts books and it doesnt show up from what I can tell but perhaps it was a later fix that was offered.