I am a new to this, so this may be a stupid question. In my '86 2.5L automatic Comanche, when I pull the lever into 4 hi, my back wheels do not turn. I was wondering if all 4 should turn? The truck runs and drives fine when switched into 4 wheel drive, but the rear 2 wheels just don't turn. I have a couple leaks coming from some where? If there is a problem, could the leaks have something to do with it?