Selecting no gears!

Hi i have a 300tdi and it would not go into any gears, Partner thought it was clutch so replaced that and also the flywheel housing as that was cracked.
Now the clutch and the housing is in, Went to try it today and it is doing the exact same thing. finding it hard to get in gears up or down and scrunching like mad. Went to check clutch cylinder tonight and checked the bell housing and flywheel housing ad both have cracked in the exact same place as before.
Any ideas would be gratefully thankful. Many thanks in advance

2 dowels ,its unheard of for them to crack otherwise perhaps a pic or 2

will get a pic in the morning when is light.
is was located on both dowels. the gearbox was flush against backing plate, and as the first housing was cracked in same place but now it cracked bell housing.

your doing something very wrong for that to happen

James would it be possible if they weren't supported correctly on the mounts could it twist and could the torque break it like a stress fracture

it would have to be very wrong

I'm intrigued by this now

we r completely puzzled.
he has always done stuff and is a mechanic and has puzzled another person who knows wat he is doing.