If you're trying to re-use the original lines, yeah. If you use a factory style prop valve and just order new lines it's a lot easier. More expensive, of course. But when you try to re-use stuff and start mixing and matching factory and aftermarket parts a lot of things can go sideways. And if you have original lines I'd just replace them. They make look ok, but as soon as you start taking stuff apart you'll find frozen fitting and brittle lines, even if they look decent.
DoctorDiff sells new lines too. For a disk brake conversion he can be a one stop shop, from factory 73+ stuff all the way to 13" rotors with Viper calipers. And you won't have to safety wire your hubs together, or be stuck with one of like 3 or 4 rim styles that have a hub bore larger than 3" like with the Wilwoods need. They work, but honestly they're not the best stuff out there anymore. They've been trading on their name for a long time, I think their advertising budget and sponsoring all the TV show stuff is the only reason why they're still popular. It isn't because they have a superior product.
