Grind going into 3rd

[OB1]

My tranny just started to grind going into 3rd after a long day at the track. It only does this when racing. If I shift under normal conditions, its fine. All other gears are fine too.

Any ideas??

I'm thinking syncros.

 

[beating4g63s]

good guess your prob right 3rd gear syncros are prob going out, just replace all the syncros. I've replaced them on about 4 of my friends cars, and please next time do a search.