synchros going or clutch, or both????

Anyone know the signs of worn synchros? I just bought my car about 2 months ago and at high RPM shifts, 2nd grinds going in and so does 3rd. It is worse when the car is cold and gets better when warmer. Could it be my clutch? I do have 93,000 miles on the car and my mechanic says I need to change both, but I don't know if he's just looking for work, you know? Who can help?!

I read the Tremec 3650 post, but I have a T-45... I figured there would be differences.. However, it seems a lot of people have the same exact issues I have with a completely different tranny..