Is that the 31581 pan?

Yep! Milodon says it allows 4.5 stroke. I'm running 4.75 with no issues.

Good deal.

?

Pros and Cons.
The new World (Bill Mitchell Products) aluminum blocks have o-rings around the sleeves. [/quote]

My 2008 KB block has O rings at the bottom of the sleeves. Coolant sealing never been an issue. I also don't believe bore distortion is a problem. [/quote]
I got my KB hemi block in 2006 (ordered in November '05) and I have yet to have any issues w/ coolant leaks. I have never heard of anyone having coolant leaks from any of the aluminum hemi blocks built in the last 20 years. The only ones I ever heard of having problems were the old versions from the '70s and '80s.


I bought my World aluminum block in 2009. The paper work says the O-ring at the bottom of the sleeve is to keep oil out. I have not had any water leakage issues once I found the correct head gaskets for this block.
We have about 15 1/8 mile passes and some street cruising miles, but not hundreds. The cam is a solid roller from Dwayne Porter . The engine is 572 " .
I bought my first 426 Hemi (Iron block) back in 1996 from West Oaks Chrysler in Cali. That was the start I needed to finally build the 426 Hemi I always wanted. I think the MP block was $1700.00 . A good investment as car parts go.

Mark