Dave,
 I think maybe the tree to bark up is at NCAR, although it's our job to be the first tree to bark up about RUC issues. The RUC2 doesn't put out PV directly (although there are tropopause level fields based on the PV=2 surface, as explained in http://ruc.fsl.noaa.gov/vartxt.html). Let us know if you want the routine for trop-level products (which includes a PV calculation that we think is best for RUC native data).

Stan