Rear drive shaft seal leaking

you may have to break the adhesive seal around the flange . Rem,ember that you will also have to pull the drive shaft (axles) to the diff. To break the adhesive seal you may use a jack and lift a bit under the pinion flange while using something like a chisel to help break the seal

If the seal is leaking, it will need to be replaced, if you have a service manual, it will show you the procedure to replace the seal. DO NOT try to replace the seal without following the proper guidelines as input bearing damage can occur. After the repairs are made, be sure to to clean the vent tube/valve on the diff. to avoid pressure build up that will cause early seal failure, this vent should also be cleaned at every oil change.

tearing the rear-end apart, replacing that seal, you might as well have new bearings put in as well!
Also this is a more "advanced" repair, having to use plastigauge(or equivalent) to get your clearences EXACT!!!
Good luck

if it is leaking from the front of the diff where the drive line goes into it you have to drop the rear of the drive shaft from the diff, if you look at the flange on the diff where the driveshaft bolted to you will see a nut, possibly about 25 to 30mm, you have to remove the nut and remove the flange off the spline of the input shaft of the diff, the nut is really tight and it is difficult to get enough pressure on the nut to "crack it" while the car is on the ground as there is not enough room to get a long bar on the socket to remove the nut. if you happen to get the nut loose and you remove the flange get a big screwdriver and pry the seal out of the diff, check the surface where the seal ran on the input shaft as it may have a groove worn into it, if it has the groove the new seal will still leak, they make a sleeve you can slide over the shaft to give the seal a good surface to run on, we call them a speedy sleeve here but not sure what they may call them there. replace everything in the reverse order that you removed it and don't forget to tension the big nut that holds the flange onto the input shaft

Mostly likely the differential seal.

Most likely, you need another rear diff. to be sure, the old part will need to be removed and inspected for damage. Sounds like some metal or a bearing got ruined from lack of lubrication, like a chipped tooth or a binding bearing. Make sure the rear driveshaft u-joints are OK. while you're at it. Have the Discovery put on a rack with the rear axle lifted, so the rear wheels can be spun by hand to listen to the rear diff. Sorry about your troubles

you need to pull the cover off the rear diff. remove the rear brake drums or rotors, remove the bolt that holds the pin in the rear end, remove the pin, remoce the c clips, pull the axles out. remove the seal. you can do this by using one ofthe axles to pry the seal out. install the new seal and reassemble. use rtv sealant to reseal rear diff and fill with about 3 - 3 1/2 qts gear lube-may take synthetic

It should be that easy if the leak is from the gasket. If it from the seal, you will have to remove the drive shaft from the differential and remove the seal and put in a new one. Either way, the repair is fairly easy.

the part is called the pinion flange seal, pull the drive shaft, remove the large nut on the flange the drive shaft connects to and remove the flange, then pry out the old seal and lube the lip of the new seal with motor oil and press it into the opening. The 7.5 hour estimate is way wrong, about 1.5 hours labor and $4 for the part.

check your rear diff vent if pluged clean it out and clean up the pinion seal.sometimes if the leak is caused by pluged vent and has not been leaking long once vent is clean sometimes the leak will stop.there is not a specific torque amount because it is rotational torque(how hard to turn pinion).there is a crush sleve on the pinion and if torqued too tight or too loose brg preload will be wrong and brg damage could result.mark and remove drive shaft.remove rear wheels,brakes,axles.so when turning pinion you dont have any drag from brakes or axles.mark the position of the yoke on the pinion.remove yoke,replace seal,reinstall yoke be sure to replace pinion nut.tighten nut until it takes the exact same amount of force to turn pinion as before taking original pinion nut off.hope this helps.