When this was still in place, I put LARGE forces on the cleanout in the middle of this and could not get it to unscrew. The tube going off the left of the picture was 3 feet long and SOLIDLY obstructed from end to end.
God help 'em they saw this day coming, and put that giant fucking cleanout there! But I couldn't open it even with pretty serious leverage!!!
The brass stuff that actually interfaced to the tub was VERY sturdy and will last literally forever. Well, except for eventual erosion I guess, when the whole BRICK house is gone.
All I really needed to do was sawzall out that one pipe, then shove another one back in there. But I wanted to get the tub plug working again and chose the hard way.