The slave, (thrust bearing on a cable clutch(, has to be in the bell housing because it what actually engages and disengages the clutch plate.
The DMF is spring loaded, it prevents clutch grab and judder, making pull away and clutch disengagement smooth. It would only need replacing if there is any kind of clutch judder when pulling away, from anti stall rpm without touching the throttle, to using 1500 - 2000rpm. This is caused by slack in the DMF springs, measured in teeth. If you have no clutch judder, and at 50k, you would not need a DMF. Any mention of grinding of the flywheel or new DMF blah blah blah is horse shite. I know 2.0L CDTi's with 200k - 300k with factory DMF and no clutch judder.
I am too old and been round the block too many times to be replacing clutches, luckily, I have used, know and trust the place who MOT's my motors 40 years, if I was told I need a new DMF, I would need one, but at the same time I would know.
To pre empt being bullshitted to death about DMF Tell whoever does it you have NO clutch judder whatsoever. You can always ask beforehand if they offer flywheel grinding, and if they say yes, tell them it is NOT to be done, if they say it is rubbish, all the better.
Ok, the friction plates wear, but Ford would be having toooooo many back under warranty. I would guess DMF should be good for well over 100k. I would say higher, but the anti stall that raises the rpm I am not too keen on,
The only work that should be carried out is clutch plate, slave, clean & bleed.