transmission trouble heres the issues.......

ok got a cable trans and it has a whine in all gears, reverse will not go in, and 4th will go into position but has a synchro grind once i left off the clutch.

anyone know what the causes are or have some insight?

Bad gears,synchro,or transmission or might be low on oil?

reverse gear is not beyond functional, just normal useage
brand new oil and full

The whine is likely from a worn bearing. Depending on when it whines you can usually tell which one. For reverse, if you put it in 1st then reverse will it go in? 4th gear or synchro is probably worn out. With all these issues you’re likely in need of a new transmission or a rebuild. Did you have all these problems before or after you changed the fluid and what fluid did you use?