Patrick,
I'm a little confused. You say left rear wheel has leak. Traditionally the rear of Master Cyl. goes to front brakes. Perhaps ABS changes that. If you meant left front, the metal line should be easy to change. Left rear is a different ball game. I would try soaking the flare connection for a day or so with a GOOD rust penetrant ( NOT WD-39 and a half). Then use a tubing wrench to try to loosen the fitting. If you don't have any luck, you can take it to a shop that can cut the end off and install a new connector with a flaring tool. Changing hoses and calipers is basically the same for the cars you mentioned.

Peter

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