Rattle after lift

So I finally bought some old man emu springs and dampers, I bought them as I believe the quality is meant to be top notch, they also only give a 40mm lift, I'm told my ex mod 110 will accommodate this with no problems, I've fitted 300lb/in rears (original were 330 H/D genuine) the fronts are 225lb/in (original was 185 std)
This has lifted the front by 25mm measured between the spring seats and the rear by the same. I now have a bad rattle on nuetral/feathered throttle, seems to be coming from the rear, I replaced the rear prop with a cheapo Britpart one but still get the noise, I removed the front prop to confirm the noise is from the rear and although very slightly better it was still there, I then went over to see Glyn Lewis (patient and top notch bloke) who thought I may have a prop problem, he very kindly checked the front and rear Diff flanges for play as well as the transfer box flanges and said all looks good, the new Britpart prop did have play in the slider so I fitted one of his wide angle H/D rear props but the noise is virtually the same, the front prop is a new if cheap one and I can't detect any play. He did say I should have no problems with such a small lift on a 93 110 and he's not seen it before.
Before I go down the road of changing back to standard springs does anyone have any ideas??
The rear axle is a Salisbury, the front is Rover, all the fluids are clean and full and the noise is worst changing from 4th to 5th or when first lifting off the throttle at 50-60 mph, once it's totally off the throttle it's fine, once back on the throttle it's fine but for that second or two it rattles like crazy.

Sorry, can't contribute with anything, but a very interesting case. I'm currently contemplating buying a new suspension kit. Really lean towards a 2 inch lift, but posts like this bring me back to earth..
Hope people here will come up with some relevant suggestions for Your problem!!

Could it be coming from the clutch or T/O bearing?

Well I didn't really want a lift at all but couldn't find the old man emu springs with standard height, they are only meant to be a 40 mm lift and that's under 2".
There's no play in the Diff flanges and only a tiny amount in the transfer box output flanges. I have had the same noise some time back with the standard suspension when a prop u/j siezed solid but it was fine once a new joint was fitted.

Island-Rover said:

Could it be coming from the clutch or T/O bearing?

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The noise does seem to come from the back axle area, had a brand new clutch, arm and thrust bearing fitted 2 months ago, was a good AP clutch as well.

Ah - not likely to be the TO bearing then! Have you had any luck tracking it down?

How about wheel bearings? Are they tight.
I had a noise from mine for months after I lifted it & couldn't find it. It was a rumble like something was not balanced & hitting the outer case if you took your foot off the pedal but stopped when putting your foot down again. New props, cranked arms & bushes back & front, rebuilt the transfer box but it turns out I also fitted new wheel bearings a few weeks before doing the lift, a quick tighten & that was my problem all along

Wheel bearings all good, a lot of people in the US have similar problems on both Land rover and Toyota after a lift, they say it's cos the Diff nose angle changes as the trailing arm angle gets steeper, it's recommended to add shims or large washers onto the trailing arm behind the chassis bush, this increases the trailing arm length slightly and rotates the nose of the Diff down slightly, the rattle is apparently caused by the transfer box and rear axle flanges not being parallel, the prop can't handle this. Luckily I had a new chassis bush kit and had the big washers, I removed one trailing arm and put on an extra 'washer' , unfortunately on the drivers side the trailing arm axle bolt is siezed into the bush centre so I can't get the trailing arm off that side without a little more grief! So at the moment I'm not much wiser, I did replace the upper A frame ball joint and that did make some difference, I'll try and sort it this week hopefully.