Disco 1 drive train problem

problem of clunking loosing drive loud banging noises I lost drive totally put it in diff lock got it home
I took rear diff out teeth were damaged and the rod connecting 2 cogs together was snapped
Took front diff out the same so replaced both check half shafts and cv's all seem ok
Put it all back together took for a test drive same thing happening
You drive along it goes clunk bang jerks looses drive but then change gear or go in reverse it seems to come back
It's confusing me but thought I would ask if anyone knows before I change gearbox and transfer box
It's a 300tdi manual L reg

Change the rear diff and the drive shafts, not the gears box and trans

Did you feel any windup in the drive system try driving on gravel ?

I have changed both diffs for good ones half shafts splines are good
No didn't feel any wind up
When it clunks it like jerks as if the it looses drive then comes back and it happens in a straight line

Try removing rear prop shaft with diff lock engaged and see how it behaves ?

prop shaft, not drive shaft.

When it first happened I was at a pay and play site I remember going up a gravel hill and not being able to get up it as my front wheels were digging a hole so I came down and thought better go home as going home it was clunking jerking loosing drive so I put it in diff lock and it drove home perfect
But I'll try it I was going to put it on 4 axle stands and start it up put it in gear

check drive flanges also

I have found out the problem it's my transfer box the small diff inside it has broken up
Many thanks for all your replies