Bit of a numpty question , the bb on mrsbeanZ SL-K crank set is on the way out – can I replace it with a ht2 type or does it need to be a megaexo one ?

If it’s a 24mm axle, then HT2 type works fine mate.

It is 24mm…….however the carbon cranks (slk,k force) that use a 1 key release use a very slightly narrower (1.5mm) bb. If you use a ht2 bb it will over preload the bearings making it very stiff and will die very quickly. The Ali ones use pinch bolts so you can just set them a wee bit wider on the preload bolt.
Been there done that (and explained it to a lot of people).
Hth

Cheers for that , no offence Mark but I’m going with Rorschach on this one .

Could you not just leave a spacer off the NDS?
That would make it 1.5mm narrower.

Just be sure you get the correct fsa one.

I second Rorschach on this one and have seen it too many times (even by other shops)

The aren’t any spacers to remove on road cranks either.