As others have noted you may have a bad ring and pinion or the pinion bearing. They can make noise for long time. The thought though is whether or not you plan to rebuild that box. The noise is coming from the pinion becoming miss aligned with the ring gear. Continued operation will damage that gear set. Having to replace the R+P adds drastically to the cost of an overhaul. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of B Feddish
Sent: Sunday, August 2, 2015 9:59 AM
To: vanagon@GERRY.VANAGON.COM
Subject: High pitched noise

I’ve got an issue with a high pitched noise from the back.  The vibrations in the noise are directly related to speed and do not change when I shift from 3rd to 4th (about the speed at which I hear it).  It does go away when I press the clutch in and coast so it is only happening when I have my foot on the gas.

This is a new one for me, what could this be? It it the tranny getting ready to go? If so, how long have I got? Is this a slow death thingy or clunk clunk stranded thing? Or is there something else I should look at.

This is an 83.5 wc Westy BTW.

Thanks,

Bryan