It sounds like you might be having issues with your differential
pressure or vacuum actuator, I can't remember which way it works.

Check the lines for leaks, or you can replace the actuator diff for a older
standard unit that does not require the actuator, and add the lockout hubs
to the outer where you have drive flanges now

Wild

It sounds like you might be having issues with your differential
pressure or vacuum actuator, I can't remember which way it works.

Check the lines for leaks, or you can replace the actuator diff for a older
standard unit that does not require the actuator, and add the lockout hubs
to the outer where you have drive flanges now

Wild

Wild, 98 in the US shouldn't have any kind of vacuum actuator in the diff.  Standard gears, shafts, and hubs with manual or auto hubs.  99+ have the vacuum crap.

OK, scratch my thoughts, I thought 98 was the change over year, isn't that the
year the new body style came out too?

My Tracker is my Avatar.  It is the same as the 1995-1998.  The Chevy Tracker is the first year Chevy put its name on it but still the older style.  Still believe it could be my hubs?  I think the noise is coming from there.

OK, scratch my thoughts, I thought 98 was the change over year, isn't that the
year the new body style came out too?

Everywhere but here.

In North America we kept the square body a year longer than everywhere else.

Yeah it deffinately sounds like you have a auto hub problem. You can pull them apart and check to see if there is any damage or ware, but you would be better off changing to manual while you have it apart.

Mine does something similar. If I don't start out in 4wd then shift to 2wd it makes that sound.  Is it hard or expensive to switch to manual hubs?

Not if you can find a used set. There's lots of companies now that sell used parts on here not to mention forum members. As far as install it's pretty simple. If I'm not mistaken theres a write up on here that tells you how.