I have a problem when shifting into 5th at like 45-50mph. When I shift it grinds a lil but when I'm done 30-35 it doesn't and my question is could it be a syncro or is it something else? I would appreciate it if anyone could help me out

 

It sounds like a worn synchro. If it grinds too many times, the engagement teeth on the sleeve will get rounded and you will also need to change the slider sleeve.