1985 300D, faulty rear brakes.
Planning to replace calipers, rotors and flex lines.
Only scared of the flex lines. Any tips to removing the flex line from the metal brake line? Penetrant like PB? Should I try to get the clip off and the flex line out of the mount first? I know to use a brake type wrench on the metal line fitting but is there something else I should be wrenching as a counter hold to trying to get the fitting off the flex line? I have about 1/2 day to get this done and am essentially terrified I will screw something up and need to change a bunch of hard lines. I don't know for 100% if the flex lines are bad, I don't get a squirt from the frozen caliper when undoing the bleeder but am thinking that at 192,000 miles the flex line aught to be changed out anyway.
Done brakes many times, flex lines on other cars (and had a lot of grief) and I just want this to go as smooth and quickly as possible as I need the car to be running ASAP. Other than the brakes, the old girl is running great with new glow plugs and a valve adjustment.

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1985 300D 197K - Semi-Daily Driver Diesel
1998 Volvo V70 AWD 226K - Daily Driver 2
1998 Volvo S70 140K - Wife's DD
2003 GMC Sonoma ZR2 Option - Rusty Truck
THE BABY 1958 220S Sedan 66K All original, never restored and never will be.