Grinding gears on shift

[cb3016]

So I have been driving my car lately and it will grind gears sometimes usually shifting INTO 3rd gear, I have been workin on my 6bolt engine and i'm about a month away from having it ready to swap in, but what good is a fresh engine without a good transmission? So what could my problem be? Am i looking at having to do a complete rebuild or just a little pop in fix it and go? What would cause it to grind only in 3rd? And yes I am pushing the clutch all the way in while shifting.

 

[cb3016]

No one?

 

[VelocitàPaola]

It could be a bad 3rd gear synchro.

 

[fourreGsixty3]

Exactly what velocita papola said. Most of the time its the 2nd gear that goes but your 3rd gear synchro is probably going.