Engine/Transmission (1998.5 - 2002) nv4500 making noise

[Hookemupman]

Today my nv4500 started making noise today going down the interstate when i let off the throttle with trans still in gear it makes a groining noise. When you come to a stop light with the clutch out and the trans in neutral it still makes a groining noise until you push the clutch in and put it back into a gear and then the noise will stop until i take off again. The truck has 155000 miles and had a new southbend clutch fe and pilot bearing installed about six months ago,also 5th gear nut was repaired at about the same time. The only thing i noticed that since the new clutch it has been a little harder to get into gear when sitting still. Does this sound like a typical rebuild or should i buy a rebuilt from somewhere. I do not know any good manuel transmission shop around my area. Thanks Jason