Drivetrain binding?

Hello, my 1999 UK Impreza Turbo 2000 has developed a strange problem, it's sat in the garage for a few years and I thought that the brakes were binding as you can't push it, 1 person can make it move a little but something is binding, removed all wheels and sorted the brakes and handbrake, even without the caliper on the hub is hard to turn without leverage, what's binding, the diff? Changed all diff oils, no better, help