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Discussion Starter · #1 ·
A buddy of mine has given me the task of installing his brand new p400 in his 99 Tahoe. (I did head gaskets with optimizer heads, ARP's, 4" exhaust, injectors etc in the summer of 2020)
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I have 6 or 7 trucks all with 6.5s, and am quite familiar with them. Never paid any attention to p400s since I assumed I'd never seen one in my lifetime.

Other than truck heads, studs & oil pan, is there anything else I need to know?
 
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Its heavier? And less likely to break for no reason?

Nice rig.
 

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Flared bumper nostrils
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Discussion Starter · #3 ·
Its heavier? And less likely to break for no reason?

Nice rig.
The Block is impressive. The heads look like optimizers.
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A buddy of mine has given me the task of installing his brand new p400 in his 99 Tahoe. (I did head gaskets with optimizer heads, ARP's, 4" exhaust, injectors etc in the summer of 2020)
View attachment 645579

I have 6 or 7 trucks all with 6.5s, and am quite familiar with them. Never paid any attention to p400s since I assumed I'd never seen one in my lifetime.

Other than truck heads, studs & oil pan, is there anything else I need to know?
I'm wondering where the fellow got that P400? Last I heard, they weren't being made anymore?
 

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Flared bumper nostrils
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Discussion Starter · #5 ·
I'm wondering where the fellow got that P400? Last I heard, they weren't being made anymore?
Funny thing is, I've been telling him that for a year...
He's very persistent.

I believe it came from here
 

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The heads look like optimizers.
You would be wrong.....

 

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I can guarantee you swapping the P400 heads to Optimizer heads is a downgrade... I am probably the only head porter or person for that matter for these motors that has cut a p400 head apart to see what the differences were, and there are many... some visible, some not, and they do have a different part number than optimizer heads...
 

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Discussion Starter · #8 ·
I can guarantee you swapping the P400 heads to Optimizer heads is a downgrade... I am probably the only head porter or person for that matter for these motors that has cut a p400 head apart to see what the differences were, and there are many... some visible, some not, and they do have a different part number than optimizer heads...
I absolutely agree, never said I was down grading on the heads. In the 3 minutes I saw them to inspect for shipping damage, they're very similar to optimizers. Never had a great look, but they do seem heavier
 

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They do have the same casting numbers but they are thicker and defiantly a different casting... optimizers don't have seats under both valves ...
 

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Site vendor Unique Diesel may have a set of P400 heads in stock, I have purchased several sets from them, if not in stock he is a GEP distributor and can order them..
 

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I believe you can still order P400s from Leroy diesel, last i checked Long blocks on his website run $5,800. Although he DOES mention on the website they were discontinued and no longer available... So i assume however many he has left that's it.
 

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Sounds like you're already aware of the need for a custom oil pan to fit the P400 in a 4x4 chassis. In case you didn't know @uniquediesel can source the custom pan for you, highly recommended as he ordered my pan for my P400. And @sctrailrider definitely knows his stuff when it comes to the 6.5 and P400 in particular. When building my P400 he caught fitment/ clearance issues with the custom oil pan, and worked directly with the manufacturer to correct the issue, so if you want to be sure of a smooth install I suggest sourcing from the aforementioned experts :)
 
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