My 59 Plymouth has the original single line master and i would like to put a dual system on for safety,what master cylinder would i need to use??
Hi Nighthawk,
Wellcome to our bunch! 
AAJ-Brakes offers a modified master brake cylinder for the 59 Plymouth. It fits perfectly into the car and with a small modification you can also use the original brake light switch.
http://www.aajbrakes.bravepages.com/comments.html
Good luck!
Stefan
sportfury1959
Ok thanks for the info!! You guys are great!