Grinding in All gears

[Hudsonterry05]

Hey, I have a 2003 Ranger 4wd manual with a 4.0, Today within the last 100 miles it has started a grinding sound from the transmission. When I start from first it sounds fine, but as soon as I put the clutch in it starts this loud grinding sound and does it all the way through 3rd gear, but stops when I go to 4th, but as long as i am at low speeds in low gear it grinds bad, and gets a little better if i keep it in low rpm. I checked the fluid and it looks great, its not dirty and it is full to the brim. I dont know what to check next but would appreciate any help.

 

[Hudsonterry05]

I forgot to add, if i stop the truck the grinding goes away until I put the clutch in from first, but if i downshift from first it does it then too.

 

[sgtsandman]

It sounds like the transmission is going to have to be opened up to see what the problem is. It's either going to need rebuilt or replaced.