Hey Fellas,

So I have encountered a progressively sudden onset of what seems to be a knocking/clacking noise (metal on metal) coming from the rear of the car. For months the car would constantly hum/slightly vibrate when in gear accelerating. This got progressively worse over the course of a 20 minute drive and turned into an assault on my nerves.

Im boosted with a stage 3 exedy and pushing around 450 HP. I do not track, but I drive in 3rd and 4th gear. Sometimes 2nd, and NEVER 1ST. I do not launch the car, ever! I am suspecting this is a Differential issue. But am unsure. The noise occurs clearly upon acceleration, and very faintly/intermittently while in neutral coasting. But as soon as its in gear.. it comes on very strong and constant. Id imagine a wheel bearing would make the nasty noise all day regardless of gear, right?

So is this a differential problem?
I am taking to mechanic tomorrow. If I find out its the DIFF. What would you suggest I do. Given my cars performance, should I upgrade to a stronger diff? Ive heard Ford or 300zx Diffs are a little beefier. I have also been informed of Puddys, but Its a little on the pricier side of what i would consider in my budget.

Or should I just OPT for another S2k diff. I can get a good used one for about 350$ Canadian dollar.

Advice is much appreciated!!