To further confuse Ruger fans the 44 Special built on a small frame with 510 or 512 prefix says Ruger Vaquero on the side.
While the Ruger 44 Mag birdshead built on a large frame with a 59 prefix says New Vaquero on the side.
Ruger will not sell Montado hammers. Charlie your best bet is to install Super Blackhawk hammers. Same profile as Montado but grooves on spur instead of checkering. The grooves actually provide better traction in my opinion.
I used them in my Cattlemans when I found that the Lee Gunslinger springs were too light and primer ignition was inconsistent. The Wolff springs were a little stronger and got rid of the primer problem.