Here's a little tidbit I found that describes oilpump differences between 5.7 and 6.1 Hemi's.

Quote:

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• Chrysler 6.1L Hemi (2005 and newer): The M362 oil pump is a new replacement pump for late model Chrysler 6.1L Hemis. It replaces Chrysler 5037687AB, and features a 15 PSI higher pressure relief spring to accommodate oil jets to cool the pistons. For the 5.7L Hemi, Melling’s M342 oil pump replaces the stock Chrysler’s 53021622AF pump. Melling’s 10342 Select Performance high pressure pump can be used with either the 5.7L or the 6.1L Hemi engines.

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