Wierd main bearing setup? (ABA)

[area53 at validpath.com (Jeff Toomasson)]

Just opened my main bearing package from Potter to plastigage the crank clearance.

But the package included 6 holed/slotted (upper) bearing shells and only 4 solid shells. This package is the one with the six-piece #3 bearing setup.

Is this proportion correct? Is the extra slotted one for the #3 lower?? WTF?? I can't tell anything from the Bentley diagrams....

thanks, Jeff