Transmission Problems

Hey guys so about 3-4 months ago i bought a 01 bullitt with a tranny problem. 3rd gear grinds when i try to shift into gear, all other gears sound crappy but go in, so im prerrt sure i need a new tranny. My gf ask'd her dad who knows about cars and he said to first change the hydraulic something, dont remember exactly what it was, and the clutch. and see if the tranny is any better. then if not go ahead and get another transmission. I just wanted to know your guy's thoughts about this, I probably need a new clutch anyways and rear end.. car was beat it seems like. but thanks for your thoughts.

thanks for replying, but do you know where to get these forks and syncros, and how much do you think it would be? because I was thinking of buying a completely remanufactured tremec 3650 from this website i found for $800 after the core rebate. and comes with 6 months warranty i thought this was better for the price but how much would all the other items be?