"clunk" in rear end

[FLAVALK]

When I take off from a full stop, I get a noticeable "clunk" in the rear end when it loads up. It's most noticeable in 1st & 2nd gear. Ya'll think this is a u-joint issue?

[Gavin_Sons]

could be the pinion cup also. you should take it all apart and check the whole drive line.

[Louis Durocher]

Agree with Gavin

[Chrisj CMA]

Don't forget the dampeners, if they are loose, Id imagine a cluck could happen

[Pete]

When mine started it only clunked on a start with slight left hand lean.
As it progressed it would do it straight up both only in low gear.

Turned out to be splines in the wheel/drive unit.

Replacement fixed it.

The splines were dry. the PO had not serviced them when the wheel was removed.
There were signs of initial paste lube, but it to had dried.

[BobB]

My pinion cup failure in 2012 started with single clunks as that spline slipped a single tooth.  I only got 250 miles down the road before the clunks turned into a rattle and the Valk stopped moving forward.

[FLAVALK]

Thanks all!