Ends up being a bad u-joint on the front driveshaft. Looked fine the first couple of times I checked it out, but the noise has been getting worse so took a look and it is bad. Installed the CDL switch so I could remove the front DS. Took a look here on replacing the u-joint http://forum.ih8mud.com/80-series-te...your-80-a.html
and not sure when I will have the time nor patience to tackle this. Will order up a new u-joint from Stevinson today, where would be good to replace it? Thanks.