Have a look at the brake's/hand brake to see if you can take off the brake drum's/brake housing if its a super, could be a bearing gone on the rear axle's if water has been in the oil, lift up the back end to see if any play there better done with the wheel's off just lift axle up and down, if play you know bearing gone...! you can always take the top off and have a look, but you have never done it before take your time.
Tony
December 2011