always.late, Actually, the older Vaquero and NM Blackhawk are exactly the same profile except the Vaquero has fixed sights. The New Vaquero has a thinner cylinder frame but all internal parts are compatible with the Blackhawk.
Except for the Single-Six, the hammers in all other Ruger SAs to include the Vaquero, Blackhawk, and Super Blackhawk will interchange. Note: several years ago, Ruger started making the transfer bars thicker and to compensate, they extended the top step on the hammers. So ... if you put a new hammer on an older gun, you will have to remove .030" from the top step or you will get light primer hits. An old hammer on a new gun might result in pierced primers.