Auto box clunk then no drive

Hi there, Been a while since i posted.

Have a Disco 1994 v8 with an auto box, was having some problems in the mornings with it sticking in 1st then it would be fine after a mile or so.

Go to drive it home the other day and no drive, so i changed the gearbox fluid, it was very brown, and all was well. so go to drive home get to a junction loud clunk no drive at all even in diff lock and the is a knocking comming from one of the boxes. i can change between high and lo and hear it engage.

Any help appriciated

Thanks

Daniel

sticking in first is govenor sticking till oil warms ,either worn govenor or something is contaminating oil ,are you sure diff lock is engaging and not a prop uj broken ,possible centre diff bust depends on how far you can hear drive going too,