My mate has recently killed his focus st 170 and it's gettin scrapped. Would it be possible to strip out his 6 speed gearbox and put it in the fiesta or is it not that simple? All you with mechanical know how please let me know

No you won't get ST170 box to fit on ST150 engine, and if you could it's no good anyway, the ratios are all wrong.

I can spend all day explaining why it won't fit if you want but it's not worth it.

No, even if it was possible to do that, which it isn't, I'm not sure why you'd want to that anyways. The 6-speed gearbox off the ST170 was awful.