Series 3 Knocking noise from rear prop-shaft or maybe diff?

Hi everyone, my petrol lightweight has a new noise and it's definitely not good. I'm trying to get as close as possible to diagnosis before I start taking bits off so here's where it stands at the moment:

I recently got round to changing all the gear oils (Gear box, transfer box, overdrive, diffs), but after that it sat for a while without moving. Then I couldn't get it to move, as if the handbrake was seized on, so put it in low range to "tug" the handbrake off, and it came free and seemed fine. (Gear changing was lovely for the first time in years!)

Then rolling down a track towards the road there was a knocking noise coming from underneath. I put it in neutral and the noise carried on as I rolled, and as I picked up speed it got louder and faster, and then turned into a nasty jarring/rattling noise. Obviously I stopped, and reversing back up the track the noise was still there but quieter.

So far I've put it up on stands. Rolled the rear wheels with handbrake on and they turn freely with no noise. Then took handbrake off, blocked one wheel from moving and turned the other wheel and the knocking is there again.

I think my next move is probably disconnecting the prop shaft and working out if the noise is coming from the shaft or the diff, and moving towards the front from there.
One thing I'm wondering is how far towards the gearbox will the problem actually be? I've never quite worked out what is actually connected to what when in neutral. Obviously when I turn the wheel the diff is turning, and the prop shaft, and presumably the transfer box is turning too? But is the transfer box disconnected from the gear box when in neutral?
(Hope that makes sense!) Cheers in advance.

Think I'd be checking out the handbrake first, slip the drum off and catch the loose bits

try with rear prop off and in 4wd, ujs in prop are a common issue but it should show whether issue is in axle or transmission, the transfer box will turn which will turn the mainshaft in the gear box but not gears in the g/box if in neutral, if you put it in gear youd have to turn engine over or press the clutch

jamesmartin said:

try with rear prop off and in 4wd, ujs in prop are a common issue but it should show whether issue is in axle or transmission, the transfer box will turn which will turn the mainshaft in the gear box but not gears in the g/box if in neutral, if you put it in gear youd have to turn engine over or press the clutch

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Ok that makes sense. Only got 2 axle stands at the moment so I guess I'd need a couple more to try it in 4wd? Useful info though, cheers.

As Freelance says I guess it'd be a good idea to check the transmission brake first. It sounds like the problem is further back than that but probably sensible to try the simplest thing first!

you can drive it down the road with rear prop off, just not too far and it will be a bit notchy in full lock so best avoid that

jamesmartin said:

you can drive it down the road with rear prop off, just not too far and it will be a bit notchy in full lock so best avoid that

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Oh right I see what you mean. I'll bear that in mind although it's parked up a tight little lane so avoiding full-lock could be difficult....

Haven't had any time to even look at it yet but hoping to get out there today.

Well I got underneath today and made a start trying to get the drum off the transmission brake, which was being very stubborn. Got the nuts off, backed the shoes off, and then gave it a few whacks but it wouldn't come loose. Then just out of interest I turned the wheel and the knocking noise had disappeared! Took it out for a drive and all seemed well again.
As someone suggested maybe it was just the transmission brake after all. Maybe the drum was slightly out of position after being seized, so was knocking on one side, and rattling when speeding up. Anyway for now everything seems better. Sorry for wasting everyone's time!! Cheers, and happy new year!