I can't seem to find the Ubercart 2.x version of USPS Shipping module!
This is the closest I could come, but I feel like I shouldn't be constructing the module from a source view. http://api.ubercart.org/api/file/ubercart/shipping/uc_usps/uc_usps.module/2/source
There was a zip available here of a spin-off module... http://www.ubercart.org/forum/support/6869/usps_shipping_dimensional_weight_shipping_osc_vs_uber
do you mean U.S. Postal Service? it is in the Ubercart - fulfillment group. i guess it came with the ubercart module itself.