It doesnt matter if i'm slow, fast, or double clutching, sometimes it crunches from 2-3rd + from 4th-3rd, really sounds like the box is gonna hit the road.

Not all the time, cos other times it wont do it at all.I'm confused now.

No problems in any other gears :)

Have you droped the oil and inspected it yet?

not yet, just fishing for ideas at the mo.

sounds like synchromesh on its way out rebuild job.

Or try Redline Heavy Shock oil, can "hide" this. I have tried it in three or four cars, brilliant. Inc my Z, but only to protect it as the box was fine.