Wheelbearing is my bet. I've killed many and they always seem to make a different noise each time.. f'in things. I assume your hubs were unlocked right? If not then it coulda been spindle bushing.

Or, maybe your brake pad caught the rotor funny? Idk theres not a whole lotta things that'll make that noise.

I'd jack up the front and spin the wheel by hand. A bad wheel bearing will grumble or feel grimy. If its a bad wheel bearing, you'll wanna fix it before you drive it again or you'll destroy your spindle.

-Scerb

http://www.scerbfab.com/carb_faq.html