Saw this old beast today (and it’s keepers 🙂) Unusually tidy example and seems to go ok too.

I agree that the backlash looks fairly typical -  I’ve seen worse. Almost certainly most of that will be in the differential gears due to worn thrust washers rather than the CWP. I definitely wouldn’t mess with the pinion nut unless there’s obviously float in the bearing. The clicking could still be a driveshaft UJ, even if replaced. It’s not uncommon for one or more of the trunnions to be slightly splayed leading to some endfloat which allows the spider to flick from cup to cup twice per rotation, making a clacking noise. The fix is thicker circlips (or beer can shims under the circlips).  Unlike propshaft UJs, which need to be free moving on both axes, driveshaft UJs are best tighter, with noticeable drag even once the caps are tapped back up against the circlips.

Thanks.  Noise wise it's not too bad, there's a whine under light load (motorway cruising) but other than that it's fine. With the one exception that I've still not resolved the clicking in the drivetrain at the rear despite now having replaced all 3ujs in the past 6 months or so.  Maybe the nosie is from the diff , or maybe the dodgy trunion was causing it.  Hopefully it'll disappear after I reassemble it this time.  If not I'll have to drive it until the problem becomes sufficiently obvious and hope that happens within limping distance of home!

I would say this is about normal for a used diff, and you can't tell where the wear is, it won't all be crown wheel to pinion back lash even with the handbrake on. Is it particularly noisy? My two cents would be that playing with pinion backlash probably isn't a great idea unless you have some reason to think that preload is low, e.g. noise changing between drive and coast?  

Remember discovering this myself early in my ownership cycle . Back in those days my local BL dealer (jyst across the street) were able to help. But not on a Sunday afternoon .

My spare for the front is a nylon one, probably from about 10 years ago when I bought a pair but never only replaced the bad one, so hopefully still good.  The rear one definitely needed doing after I noticed some vibrations. I'll let you know how the kit installation goes.  

All useful bits of information, I agree the order of discovery is suboptimal. One more for you; most trunnion kits sold these days are barely fit for purpose if at all. I prefer the Witor/Superflex polybushes on the front at least. Not cheap but they fit properly and last very well. I believe they are also available for the rear, though I’ve not yet tried them. Bella needs a pair…. https://www.superflex.co.uk/proddetail.php?prod=SF375-1850KSS Might be available from elsewhere too.

Carney offended him. What a suck!

I have a lot of play on the diff input video here: This is with the handbrake on and so no output movement.  This diff has a castellated nut with split pin, so shims on the input.  Is there anything I can do or is it just on its way out?    

This was the response: My father was in the Western desert ( he was in operation Compass and in Tobruk during the second siege ) but he didn't get as far as Italy.  He was on battlefield ordnance-clearance but he didn't talk much about that - it included having to enter knocked-out tanks to dispose of unstable and unexploded ammo and you can guess what else might be in there.  His luck ran out in 1942 when some dodgy Italian shells he was dealing with exploded prematurely.  He spent a long time in hospital while they put him back together.   Stlll, he fared better than his elder brother who was lost on HMS Barham when it was torpedoed and blew up in 1941.