Updated: Jan 31, 2022
chances are, if you've never changed the frame rail fuel hose yourself on your X frame car, then its never been changed and its ready to crack. i can't remember the last time we had one of these cars in here that DIDN'T have the original hose. i think why people/mechanics don't change it, is they see that its clamped down inside the spring pocket, so they don't want to bother with it. to many mechanics, it probably looks like a pain in the ass that doesn't pencil out to bill-able time, so it gets left for someone else to deal with.
there's a couple different ways to address it. you can hook new hose to the old hose with a barbed adaptor without any clamps on it to create snags, and pull the new hose through. i do it like that probably half the time. depends what kind of mood i'm in. for the sake of the article and showing it can easily be done the other way, i'll explain how to do it the harder way:
remove the old hose completely. start be flipping up the clamp that holds the hose in the spring pocket. that can be achieved via using a prybar. don't try to remove the screw that holds the clamp down. drag the old hose out from the rear. toss it aside. you will need to replace it with 5/16 hose. don't even bother trying to use 3/8". its simply too big to fit through the holes and its not what the car is supposed to have on it, anyway. cut your new piece a foot longer than the old hose so you have more material to work with and pull on. start from the front and not the rear, through the hole in front of the crossmember and spring pocket behind the fuel pump.... use the natural curve of the hose to your advantage as you feet it through, twisting it to get the hose to progress in whatever direction you need it to... don't worry about the hold down clamp in the spring pocket until the very end. right before the wheel well sheet metal, there's an oval hole in the outside of the frame rail. get the end of your new hose close to it and use needle nose pliers to get it fed out. get good length of hose through that opening before feeding the hose through the body support bracket stemming off the frame. once hose is threaded through, front to back, get your inner spring hold down clamp secured on the hose via pry bar against spring to crimp it back down over the hose... before cropping the hose to correct length on both ends. you can add an extra fuel filter between the frame and the fuel pump if you feel like it, or simply don't want a fuel filter on top of the engine. that being said, DO NOT use a 3 prong bypass filter for AC applications, mounted down below the engine. it has to be mounted up high in the stock location.
side note: if your car is bagged, i recommend not trying to run the hose in the stock location, inside the spring pocket. run new hard line on the outside of the frame rail, away from the exhaust.