FG XR6 Turbo gearbox issue?

[Danross85]

Hey everyone, My 2010 FG XR6T ZF6 has been on the dyno today and on its last few power runs after you let off the accelerator about 5-10 seconds later there was a massive clunk that sounded like a gearbox was about to come through the floor. After the clunk it was slip out of performance mode into neutral and about 5-10 seconds later would go back into gear by itself. I have done a bit of research and cant seem to find anything gearbox related other then diff bushes but this thud seems to be coming from the under the front seats. Has anyone come across a issue like this before and figured out what it is? gearbox serviced 7000kms ago does not slip gears or have rough changes just having this issue on  de-acceleration. Any help would be greatly appreciated cheers.

[k31th]

check the selector, see if it's broken... if it isn't, it's probably more serious

[Danross85]

will take a better look when it is on the hoist tomorrow it currently drives and cycles through the gears fine until its under hard load on the dyno after a power run it just makes a horrible sound then slips out of gear into neutral. But ill have a look at the selector first thing in the morning.

[k31th]

well, if it's shifting OK out of load and isn't shifting well under load, it's more serious and you've probably got some clutches wearing prematurely.