So Rat Patrol, I'm really curious what forum / post you read about the Mopar crate GEN3 426 being a different, outer dimension than the other Gen3s. They're just plain wrong, which I think is important for the OP to know.
But it wasn't specific to Indy product - which is where you may be misreading my previous post.
It's a simple issue - on a couple of forums I read of crate 426 cui flat tappet Hemi motors being referred to as "Gen 3" - as opposed to the original FACTORY made 66-71 motors as "Gen 2".
This is the reason I believed the OP was referring to a crate "old school" hemi.
If this terminology is "wrong" in your opinion..... I'm happy to acknowledge it as I'm a victim of misinformation....(probably not a first on the internet....)
But in my defence.....it's not as if I have nothing to contribute on the topic assuming it's a 6.1 block....so clearly I picked it up from somewhere.