Diagnosing real wheel bearing noise?

[Kevin Trent <trentkc@domain.elided>]

My '73 spider with 150k miles has developed a noise that I suspect to be 
the passenger rear wheel bearing.  Here are the symptoms:
- a growly rumble that increases in pitch and loudness with speed;
- no change in noise whether the car is turning left or right;
- can't tell which side this noise is coming from.

But there is an another noise that makes me wonder if my initial diagnosis 
is correct:
- this additional noise definitely seems to come from the passenger side;
- this noise is muted; it can be heard when reflected from the side of the 
road back to the driver, for example when driving past guard rails, a wall, 
or next to a van or similar slab sided vehicle;
- if I open the passenger door while driving the sound is much easier to hear;
- the noise itself is unlike my prior experience with bearings - it is a 
"clickey" tappety, popping click-tip-tack sound that seems to have an 
irregular cadence, not directly related to speed, but more noticeable at 
higher speeds.

My questions:
1. Does this sound like the rear wheel bearing? If not, what - the 
differential?  Any other symptoms or tests that might conform a diagnosis?

2.  If this is the outside rear wheel bearing, will it suddenly have a 
catastrophic failure, or will it gradually get worse (I have a 25 mile 
drive to work, but I don't want to be left on the side of the road or have 
it seize and cause an accident.  I would rather wait to take it down for 
repair until after the convertible season is over).

3. Is there a trick to removing the press fit retaining ring (this is a 2L 
LSD axle).  And the last time I had to do it , the bearing was also very 
difficult to remove from the axle shaft.  Advice?

thanks,  kct  //Powell, TN
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