Odd Crank Bearing Question

I'm stumped on this one....

I was perusing the Mahle/Clevite bearing catalog today and ran across 3 different PN's for the non-360 main bearing sets . The descriptive difference is this:

• MS963V: Engines with 3.305/3.375" main bearing flange OD; listed for 273/318/340
• MS1344V: engines with 3.460/3.530" main bearing flange OD; listed for 318 only
• MS540H: There is no mention of main bearing flange OD; listed for 273/318/340

The individual bearing listings in each set only differed in the #3, thrust bearing, so I assume they are referring to the thrust surface on the crank. And this one bearing set MS1344V is only for the 318 (both LA & Magnum). Soooo.. are there 2 different thrust bearing surface sizes for the 318 and how do you know what came in what? Is the larger for a manual trans crank, or what ??? Is it important?

One other odd thing: The Mahle/Clevite catalog lists the MS963V as having grooved upper shells and ungrooved lower shells (normal configuration) but one catalog listing says they are grooved upper and lower. Does anyone know a PN for full groove mains?