Problem replacing shower hardware

The shower hardware in one of our bathrooms is 40+ years old and is leaking like mad. I got all new replacement hardware but the old piping is so coroded that I can't take it out. I've sprayed about 3 cans of Liquid Wrench on the connections to loosen them and no go. I could cut them out, but since it is impossible to replace the lines going up to the shower head and to the faucet, and I couldn't remove the piping from those two connections... I'd be up a creek.
Any ideas? I'm tired of banging on the two pipes with a pipe wrench, I just want to get it all replaced.
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Brian Henderson wrote:

Is this galvanized iron pipe?? Are there unions?? No idea what your arrangement looks like but one method is to heat the fitting with a torch to expand it. Or cut the galv and rethread it. Or use a Dresser compression fitting.
Jim
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Yes, sorry. It's galvanized iron. The problem is removing the faucet assembly itself. The two water supply lines come off just fine, it's the iron connections to the shower head and the faucet itself that are completely corroded. Unfortunately, this is an old house and the previous owners cut a hole in the tile and the space I have to work with is about 3'x18", just between the two studs where the hardware is mounted. If I cut off the iron pipe, I still have to deal with the unions running up to the shower head and down to the faucet, neither of which can be replaced as they are just as corroded and I couldn't remove them.
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Brian Henderson wrote:

If applying heat from a torch looks too dangerous in that space, use a Sawzall to cut the pipes off to the shower head and the "faucet" (spout?). For the shower head, think about snaking a length of copper up in the wall space. Work thru the hole in the tile to remove the existing EL for the shower arm. Put a "drop-ear EL" on the copper to attach to wall/stud. Alternate is to use a Dresser compression fitting on the existing galv riser. Ordinarily I wouldn't use one inside a wall, but the shower riser is low pressure.
For the "faucet"/spout, saw the old piping out and replace with copper or even CPVC.
Jim
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