95 z34 shifting problem

Hey everyone, I recently bought a 95 Z34 and it has a problem shifting. It will shift from 1st to 2nd ok but it will not go into 3rd. It shifts into all the other gears just fine just not to 3rd. So the car tops out going 35 mph and it starts reving out up at 6000 RPMS. The mechanics and people tell me it's the tranny but I'm not sure. Can anyone tell me specifically?

You need to get a proper scan tool, or take it to a good transmission shop, and they will run the car with the scan tool to exactly tell you if its time for a rebuild.