PI vs NPI engine block

So I bought my 2002 mustang gt a little over a year now, and recently pulled off the intake manifold to replace the gaskets because i had noticed it was leaking,I noticed it was a dorman intake, but I just assumed they had somehow managed to break the original Ford one, and well...my heart sank when I saw the tear drop shaped ports. for some reason, one of the previous owners apparently had swapped either a whole NPI engine in, or just the heads. My questions is, is there anyway I can tell if the engine block itself is PI or NPI because I’m curious if they had swapped the whole engine or not, thanks!
 

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I believe they're referring to dowels for the main bearing caps. The bell housing should already have dowels (to locate the transmission when installing), but there are a couple different main cap setups, depending on the block.
 
The castings are on the drivers side of the block. The difference in dowels is Romeo or Windsor, so an older Romeo NPI block would still have the jack screws, which you can see in the pic, along with the casting numbers.
 

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Also, (because I failed to actually answer the question for the sake of commiseration) as far as the differences between the actual blocks themselves, there are none except between Windsor and Romeo castings. The pistons have a shallower saucer shape dish in the NPI blocks, and they are deeper and more angular on the PI block pistons.
Why anyone would put NPI heads on a PI block, I don't know. Considering both of our cars had NPI engines in them just tells me not everyone is familiar enough with the modular engines to know the difference when they need to swap them out. "A 4.6 is a 4.6, right?" Either that, or they were put in for a quick sale. Either way, it worked out ok for us.
Sure you knew that stuff already, but putting it in for the sake of anyone that comes across the thread searching for something.
 
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Also, (because I failed to actually answer the question for the sake of commiseration) as far as the differences between the actual blocks themselves, there are none except between Windsor and Romeo castings. The pistons have a shallower saucer shape dish in the NPI blocks, and they are deeper and more angular on the PI block pistons.
Why anyone would put NPI heads on a PI block, I don't know. Considering both of our cars had NPI engines in them just tells me not everyone is familiar enough with the modular engines to know the difference when they need to swap them out. "A 4.6 is a 4.6, right?" Either that, or they were put in for a quick sale. Either way, it worked out ok for us.
Sure you knew that stuff already, but putting it in for the sake of anyone that comes across the thread searching for something.
I was thinking maybe a timing issue and they noticed quickly ( after replacing timing components maybe?) and they cranked it once before they heard it, so enough to bend valves but just leave a couple marks on the pistons? But it doesn’t matter now I guess:confused:.
 
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If you are taking the heads off anyway look at the dish in the piston. The npi pistons had a smaller dish due to the larger combustion chamber on the npi heads. The pi block will have a larger dish that runs out a little closer to the cylinder wall. I can post pics as I have several pi and non pi block store down right if it would help
 
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