Which section of the line are you trying to replace? All of it?
If you're talking about the line from the tank to almost the engine, it should be hard lined Parker:
3/8 on the return, and I think supply is 1/2".
On my 2000 Endeavor, somewhere around the transmission and rear axle those plastic lines change to standard rubber/flexible hose.
If you remove the hose that you want to replace, take it to a local hose shop - they will make you an exact replacement. If you aren't sure where to find a local hose shop, Googling "Parker Store" can usually help you. It sometimes takes a couple attempts to find a good shop, but once you find a good one, it's extremely valuable.
2000 Holiday Rambler Endeavor, 40', Cat 3126B diesel pusher, Dual Slides, fully remodeled
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