I have an '84 F250 with the 300 six, NP435 4-speed, and 4WD. It starts, drives, and runs pretty good. I use it for a yard and garden hauler, so it's not a daily driver. It's got 145k on it and I maintain it.

Lately, though, it has started making an intermittent sound that is like a bird chirping. This almost always happens at speed but pushing in the clutch pedal makes it wind down and stop. When I let the clutch out again, it may or may not start up for a while. I'm thinking that this is a throw-out bearing on the way out. If it is, how big a job is that to replace. The clutch works fine and does not slip at all. Any idea how much a local shop would charge to replace it if it is the throw-out bearing? Thanks for any assist.

 

Sounds to me more like the transmission input bearing. I would check the transmission oil level and possibly drop the transmission to have a look

 

Most of the time the Throw out bearing makes funny noises when the clutch pedal is down.

 

OK, guys, thanks for the heads up on possible sources for this sound. I drained and refilled the trans last year (yeah, it was nasty) and it doesn't leak at all so it's probably still full of trans fluid. I will check it to be sure, though.