I was thinking that the NM BH just had the new transfer bar mechanism. Thanks.
You are correct here, the words New Model are stamped on all New Model Blackhawks indicating that they have the transfer bar mechanism.
Since ALL fixed sight Ruger revolvers (Vaquero and New Vaquero) have a transfer bar system and have only been made since 1973 (since 1993 to be more specific) they are ALL New Models.
I can understand how this can be confusing, especially since people make this more confusing than it has to be by continuing to refer to their Vaqueros as "old model Vaqueros."
A new model Blackhawk (or Vaquero) can take any Ruger only load you care to feed it.
A New Vaquero in .45 Colt requires standard loads (no "Ruger only" or "+P" loads); a New Vaquero in .357 is plenty beefy to take hella hot loads.
Hope this helps,