gear box noises in 1st only

Hi there can anyone help with this.
I have 110 military with 200 disco conversion. has been great drive for last two years. but has just started making rattle / grinding noises in 1st gear when you accelerate, as you go faster the noises go away and no noises in ant other gears. oil levels good recent new clutch when we did the engine conversion. any ideas would be appreciated.

thanks

Pips

the first gears are probably worn so have slack in them, or maybe your bearings are on the way out.

(Hope what happened to me the other night dont happen to you)

thanks for that, you probably right, something worn out or slack, what happened to you????

input shaft bearing collasped on the motorway at 1.30am whilst going on holiday