If you see gear lube leaking from the seal on the left,or the seal inside the brake drum,replacing them will not fix your problem.There are 2 seals inside the differential that seal the gear oil.The seals you can see leaking are to keep water and mud out,the bearings are sealed.You have to pull the axle,pull the center section of the differential,then split the differential,to replace the inner seals.It is not hard,and you can do with standard tools,just be sure to put the shims back in.Because of this design,the axle splines,inside,get rusty,then wear.I recently did my old beater,the axle was very loose in the splines,when I pulled it out,the axle splines looked terrible,but the splines inside the ring gear carrier had much less wear.From the factory,these axles are a press fit,but,from info I gathered,does not last long.I think the axle is softer than the internal splines.So,when putting back together,I installed an aftermarket axle,it slid in snug,and had no play.I called a friend(old Yammer technician) and he said as part of a service for farm customers,they slide out the axle and grease the splines,1 to 2 times a year.I have heard some serious mudder/high water guys drill,tap and install a grease fitting in the axle tube,and pump it full of grease.Also,if you loose the left axle bearing(you will),by the time you notice,the bearing race might be very corroded to the aluminum housing,very difficult to get out,but,if you pull the differential apart,drives out easy from the inside.OK,that's my information donation for now.