1990 Defender 90 200TDI. replaced the rear output seal and fixed one leak due to no oil in it when a seal blew and damaged my flange.

Since I have blown that seal I have a feeling I blew the bearing. Is this possible? I drive and hear a whining from the brake drum area as I was driving without the cubby in the middle to listen and locate. If it is the bearing is it easy to replace without dropping the transfer box?? And is there instructions anywhere in the forum to follow? Thanks in advance for all your help!!