Dif Chatter?

My beloved VX started making a 'clicking' noise about a week ago. No Isuzu dealer in town so took it to a ma and pa shop and they thought it was an exhaust leak. However, after thinking about this, I am convinced it may be 'chatter' from the front dif. So, can anybody help me diagnose this by answering the following;

1) For those who have heard dif chatter, does it sound like a metallic clicking?

2) Is the nosie worse when it is cold, and sorta goes away after it is warmed up?

3) I recently moved from balmy North Carolina to northern Wisconsin, and it is sorta colder up here, and by coincidence, I noticed the clicking sound when it started to get to 15 degrees at night.

4) I used royal purple 75W140 in North Carolina, what should I use in the colder climate? 75W90? And probably the limited slip gunk?

Thanks

I think my Rancho shocks are loose, they make a clanking sound every so often... Something about the shocks being a hair too big.. check 'em if you got'em

A little more inquiry if I may.

Does it only click during acceleration or does it click at idle?

Does it click during coasting?

How are your CV's?

There are tons of things that can make a clicking noise down there, unfortunately finding it is just a matter of elimination.

I can still hear it at idle, or when coasting, or when car is in neutral, but just barely. It is much more pronounced at acceleration.

have you ever heard lifter tick before and able to eliminate that as a possibility?

not sure how common it is on the 3.5's, but the 3.2's are notorious for it.

does your diff have proper gear oil level in it??? or is it a bad CV?

If the noise gets faster when gassing it at a stop it is most likely lifter noise, I have a little tick. It could also possibly be a bearing that went out on A/C, alternator, etc. It is not your differential it makes the sound at idle.

I guess if your exhaust manifold pulled off it could be vibrating against the block and give a tick? There are a lot of things it can be, just take a stethascope (sp?) and listen to different parts under the hood and see where it is coming from.

Could also be the nut on the EGR tube has come loose. This is a fairly common problem that will sound like a ticking noise and gets louder at higher RPM's.

Jay, you are the man. The mechanic claimed the EGR nut had worked loose. Simple tightening resolved problem, and since I graduated with the mechanic, NO CHARGE. Thanks to everybody for your comments,and have a great turkey day.