Reposted so that it will show up as a 2.3 add-on, and pop up in the search feature. Original text from USPS Methods 5.2.1 displayed below.

5.2.1 File drop for fresh osc2.3.1 Install fulluvscents 31 Jan 2011
This is not a full package release except for the following:

This package is intended only for fresh installs in unmodified osc2.3.1 stores. Drop the files, replacing existing files and make a couple of changes per the instructions.

For full install instructions on any other osc version or on modified osc2.3.1 stores, see the previous full package upload.

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