Just to make clear what Bob Wright is saying...
In Ruger speak... "Old Model" means three screw action.
"New Model" means two pins and a transfer bar action.
The "Old Model" predates the Vaquero line by a bunch of years, therefore there aren't any "Old Model" Vaqueros.
In Vaquero land.. there are "Vaqero's" which are the orignal large framed guns and the "New Vaquero". These are built on the mid sized frame. They all however have the "New Model" transfer bar action.
I know ... confuing.