I have a 1984 Chevy k10 4wd with an sm-465 4speed manual paired with an np 208 transfer case, and when I'm in third gear going at speeds from 45-55ish mph I get a strange noise coming from the transmission. I've gone down the road with the noise being made and put it in neutral while the vehicle is still moving and the noise stopped immediately. The noise also stopes after hitting 60 mph. I've taken the inspection plate off, and stuck my hand in as far as I could go but I didn't feel anything really lose. I've changed the fluid as well thinking that may of been the cause but no luck. I've had no issues with performance since the noise has started to happen, but I'm still worried. If you have any idea what it could be please let me know.
Thank you for your time.
"Strange noise" doesn't give us much to go on. Can you be more specific, or put up a video demonstrating the noise?
Its hard to describe but its like something is trying to work its way loose, metal on metal, or I will try to get a video of the noise when I can but I don't think my phone will pick it up very well.