I installed a double action pump in my 49 about seven years ago. It's still working fine and I'm transferring it to the 235 that's replacing the tired old 216. I'm installing a PCV system on the 235 so the vacuum boost will probably be helpful.
My truck had a 6 volt auxiliary vacuum pump on the firewall when I got it. It had been disconnected long ago and I didn't bother trying it out. Maybe there's a 12 volt version out there somewhere but switching to electric wipers would probably make more sense. That's my plan when the old vacuum wiper motor gives up the ghost.
