Help identifying front-end noise

[rgunlock]

I'm just finishing up restoring my 78 K15 and during test drives I'm hearing a noise from the front end I haven't been able to identify. Its kind of a "swish-swish-pause-swish-swish..." noise. The tempo increases/decreases with the speed of the truck. I got a ChassisEAR setup and listened around and it seems to be coming from both front wheels.

Figured brakes. I'd already replaced rotors and pads so I went ahead and replaced the calipers as well. Still have the sound, but realized that it doesn't go away when I press the brakes. If it were pads hitting high spots on the rotor I figure it would stop when the pads grab.

Only thing left that I can think of is something in my locking hubs, but I've also replaced wheel bearings and lubed everything up several years ago before this became a restoration project. Can't think offhand what's in there that would make this kind of noise. Seems really loud when I drive past a solid fence along the road.

Any suggestions on what to look for? Both hubs are in the free position - haven't tried locking them in yet.

Thanks, Rick