GT3 - noise when backing up

[Dane GT3]

All

bought a used 2004 GT3 last month.
Car had 12K miles, now about 13,500.

Looks to have original tires but aftermarket (performance friction front rotors) - still have a terrible brake squeal - ordered some parts from Pelican, just haven't had the time to install. Anyhow different question this time.
According to the seller - dealership out of Dallas, the car was not tracked or raced !!

Here is my question:
When backing up and turning at the same time, all at low speed, I hear a klonk, klonk or a noise similar to a 4 wheel drive car when in 4 - low and turning.
I know that the car has limited slip and some noise could be the result of that but the noise i hear, seams almost like a binding cv joint or ring/pinion noise.
Could it be the result of low transaxle fluid level??

Any input or suggestions will be appreciated.

[Matt Monson]

It's likely the LSD. And tracked or not, the LSD probably isn't working...

LSD buster - Rennlist Discussion Forums

[88carrera]

My wife's BMW 325i does exactly the same thing. Solution? Time to change the differential lubricant with new Mobil 1. Works every time and costs very little. May be worh your trying. Note: the only lubricant that has provided the cure has been the Mobil 1.