I know by now that the default arm for carrying a body is the left one but when it becomes useless ( 0 or less than 0 health) it becomes glitchy and the bodies you carry on it also becomes glitchy and, in my case, sticks to your body sometimes.
So my suggestion is: if the left arm (default arm for grabbing) is useless change to the right arm and if both arms are useless then you cannot grab anyone at all.
