Bearing noise on Salisbury rear axle

Hi
I have what seems to be a worn differential bearing on rear Salisbury axle on a 94 defender 110 pickup.
Differential is leaking oil from the front despite a replaced seal and there is a kind of grinding knocking noise from the rear in drive.
It seems I have limited options, as everyone I have spoken to in terms of a fix can't do it or don't have the tooling. Or I have to find somewhere to keep my Landrover without a rear axle to have it sent away for upto 45 days to have it fully refurbished by simmonites. ( They currently don't have any units in stock)
Final option is to replace rear axle with td5 axle and diff, which I'm reluctant to do as I'd like to keep it as original as possible. But I'm also a little reluctant at the cost of a refurbished axle.
Any suggestions or recommendations for a fix would be very welcome, cheers

Before you go anywhere check the condition of wheel bearings, shafts and hub drive flanges. These are common causes of the noises you describe and are easy to replace and not costly.
Check the diff input flange on the diff for any side to side and up down movement, A bit of rotational free play is fine. The land the oil seal runs on needs to be in good order for it to seal, if rough replace the drive flange. Having the axle up on stands and rotating wheels/shaft by hand can help track down bearing troubles.