[Healeys] Mystery noise

[Roger Grace]

AH people - fighting a noise in my BJ8 that may or may not be serious.Reluctant to tear out the tranny unnecessarily and then to find it was something simple !
 Notice it at low speed (probably exists at driving speed but too much wind and engine 
noise) if shift to neutral and cut ignition to minimize engine and exhaust noise.Noise is pulsating - like a tire with a bad spot but seems to be at 
prop shaft speed. At first thought that it was at wheel speed and from R side.So changed out the R wheel bearing.No improvement Then while looking below noted that universals had some play.So changed out both universals.Rear brakes not dragging and no binding of wheels.No improvement. Did listening on hoist with others listening too. Consensus was that there was a noise at rear OD area as well as the pulsating one.
So pulled annulus in situ and replaced both rear bearings. Quieter but still the pulsating noise while coasting in N. Sound file enclosed is a road test from about 15 MPH then shift to N and cut engine. Tunnel cover off.
Able to replicate noise with engine on axle stands but not by turning a rear wheel by hand or with an e motor.Noise does appear to come from transmission.To verify is not diff removed one of the rear seats and noise doesn't appear to be coming from diff area.
Disconnecting prop shaft to isolate diff not possible as need the inertia of the rear wheels to produce the pulsing. About 5k miles ago I changed out the larger OD front bearing (sourced from 
Moss ... ?) in the OD.OD works fine and transmission shifts and works OK without unusual 
noises.The pulsating/cyclical nature of the noise baffles me and not consistent 
with a bearing failure ?
Given that it occurs in neutral with no gears meshing it surely is not a bad gear tooth etc.
OD not engaged so it is locked so not likely there.
Removed gearbox top cover and did inspection - nothing obvious.
So to my mind this only leaves the GB rear bearing ?Or maybe a broken circlip or thrust washer and probably on main shaft external to gearbox ?
or half shaft ?
Any comments/thoughts appreciated from the more experienced among us.Tkx rg
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20200820/90b5b081/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Road cover off.m4a
Type: audio/mp4
Size: 708959 bytes
Desc: not available
URL: <http://autox.team.net/pipermail/healeys/attachments/20200820/90b5b081/attachment.m4a>