I have a 95 Tacoma. I notice that when my pickup is in neutral there is no noise. When I put it into gear i hear a noise that sounds like gears running together unlubricated (best way i can describe it). All fluids are topped off, the noise pitch gets higher the faster i go. I notice it through 3rd gear and in reverse. It doesn't sound horrible just annoing. Any ideas?

 

Most likely main bearings, drive it till they fail or when you do your clutch, and be sure you have gl 4 gear oil,