Knocking when going in reverse?

[Oooole_E30]

When im going in reverse theres like a knocking noise underneath the car. what can cause that to happen

Thanks.

[Cabriolet]

manual car, with weighted drive-shaft?
else: bad CSB/guibo

[Oooole_E30]

ok. i wasnt really sure if it was the guibo or driveshaft.
thanks

my bad forgot to put manual tran.

[Cabriolet]

Im not sure what you are saying in the first sentence. But if you shift linkage has started to fail, when you shift in to reverse, the linkage can rub on the driveshaft. It can cause a scraping sound. If it is the guibo/CSB it will be more of a "thud" sound.

[StreetMafia21]

r u drunk??