Mopar U-joint interchange help??

My '55 Plymouth uses Ball and Trunion style u-joints. Mine are nearly completely worn out. Looking for replacments, I see that most of them are advertised for specific vehicles, not a broad spectrum like you'd expect. That begs the question are they all actually different, or just advertised that way? What will interchange with my '55 and what will not? Thanks for the help

 

Theres a company that offers a converion to run the later modern u-joint. http://www.iedls.com/page15.html

As far as replacing your ball and trunion, try: www.oldmoparts.com

Good luck!