Well I think I lost fifth and sixth gear today, but hopefully not. Whenever I put it into either of those gears it just makes a grinding sound. It never went into fifth very smoothly anyway. Can anyone confirm this? And if so is it just the synchros that need to be replaced or is there more? The car is a 95 z a4---->m6 conversion with full bolt-ons minus headers and 105,000 miles. Any input is greatly appreciated.

 

Had the same problem with 3-4 on mine. The synchro was toast and the gear had some tooth wear. All depends what the parts look like when you have it apart weather you do the gear too.