Cracked Exhaust, Typical of these castings. Question about blocks

Tearing into truck to do some well deserved repairs. I knew the manifold was cracked already, but it has grown since last time I removed it. Posted pics...
Attachment 5036
This is the replacement that was installed by Mitsubishi when they were forced to recall vehicles for cracking. Seems to me that the recall should continue as long as the manifold is in use on american highways, but it has since been removed from the listings of their responsibility.
I have one that is not cracked for the reinstall.

I also have a technical question concerning these wideblocks/narrowblocks. I did some visual comparing to 2 different blocks and I noticed that the engine plates are what is being measured to determine the differnce from wide and narrow. If this is true, would not the blocks be the same and only the plates are different? It surrprises me that Mitsubishi would make such a change in their engine block manufacturing to fit a transmission. The most cost efficient would be just a plate change and keep the short blocks all the same.
I look at this Automatic G63B and the block (iron with pistons installed) look exactly like a manual trtansmission engine block, Minus the engine plates of course. Are these actually different beyond the plates and if so, what makes them different. If you removed both engine plates from both style engines, would you be able to tell what was wide and what was narrow?

Here is a photo of an Auto and a manual engine and their plates. Why can't we use the block from, let's say the automatic and bolt it up to the plate that you removed a manual transmission block from? Seems to me they should call them wide plate engine and narrow plate engine, right?
Attachment 5037

Didn't know they had a recall. Mine is a 2.4L tho and they run the same manifolds or same design.

It's measured across the 2 lower mounting holes on the block. The plate is just a dust plate. It does nothing more then keep the dust out and make the spacing between the block and trans correct.
So the blocks and trans are physically different. This is a wide block seen below.


http://www.mightyram50.net/vbulletin...4&d=1307310824

It also depends on the year of the block - most blocks after 86 were wide blocks regardless of displacement. All 2.4s are wide blocks.

I think they should of given the wide or narrow blocks an additional letter, for example G63BW for wide maybe. Just seems like so much trouble to create an engine block casting 1 inch bigger then the other.
Just a weird thought, I wonder if the CAD guy fell asleep on the job or what? I know there is a reason behind it, but it sure seems like an expensive change for whatever the reason.R
The earliest wideblock I found was a 1987 with a production date of July 1986 Automatic transmission (overdrive) which falls into what Pennyman says.
Thanks Camoit, though my pictures don't show clearly...passenger side of the plate extends much farther then the block does, but it is matched with the trany, covering a large area that would be a hole if not plated this way.
Is there any images of a comparison of a wide and narrow block engine? Seems it's always the bellhousing being measured, though I'd like to see the engines view in a side by side (wide narrow) where it meets up with trany.

Ya, they look the same just 1 inch closer on the bottom bolts. The uppers are the same.