Defender 200tdi LT77 noise and rebuild

Hi Guys,
1991 Defenderc110 200tdi with Lt77 gearbox. I've got a chatter in any gear when a depress the clutch. When shifting down this happens mainly and 3rd is by far the trickiest to find or loudest chatter, again mainly when shifting down.

I can be sat at a roundabout in 2nd with clutch down and it starts to chatter sometimes.
I'm told it could be either the clutch release bearing but probably the synchros wearing.

I have started towing in the last 3 months so perhaps related.
I've done a full flush of the box which has made no difference but old wild looked pretty sad.

I'm told a box rebuild would be the best option as I have looked at the stumpy r380 option also but cost and mods seem unrealistic right now.

If I go for the rebuild, a seem to remember but not completely something about getting an uprated bored shaft for the oil to pass through, could anyone help elaborate on this poor description please.

As always much appreciated in advance for any help.

If i were you I woud give Ashcrofts a call and get advice on gearbox.
and speak to Luke at LOF about Clutch side.

Lightly lift clutch, if rattle goes away then suspect release bearing.

You need the cross drilled gear, but some lt77 input gears cannot be had cross drilled, 26/27 teeth rings a bell?

Dod you know the lt77 has a mesh filter that you can access and clean? this will give you a good idea how bad/good the gearbox internals are.