any tips on loosening it?

The big nut on the end of the axle is tourqued to (believe it or not) 450 foot pounds and if it has not become loose on it's own you have a booger to get loose sometimes. The best thing to use is an old timey Ford hub puller but I'm almost sure you don't have access to one of these.

If you can have a little patience you can remove the retainer lock ring from the axle nut and then loosen the nut a couple of turns and re install the retainer ring and drive the tractor until the hub loosens itself.

The early 8Ns have only one axle seal and it is more prone to leaking than the 51/51 8Ns which have an innner and outer axle seal.

You can use my home made fix to prevent it from leaking in the future if you want to try it. If the hub is not extremely tight so that you have to have a puller to get it off I think you can replace the seal yourself. If the hub is tight that is a good sign you might get it to stop leaking.The problem with the 48 8N is that it does not have an inner seal like the 51 and 52 do. If the hub is loose on the axle and it can't be tightened because of the spline being worn too much to allow any more tightening then you will not be able to stop the leak the conventional way unless you replace the axle and hub. I hope that is not the case.

If the axle is worn too much to allow it to be tightened then you might consider my fix for the leak and leave the hub loose a few more years. To fix the leak my unconventional way you pull the axle away from the axle housing about 6 or 8 inches and wrap the axle for about 6 inches from the outer end of the axle that is exposed with teflon tape.Wipe all the oil from the housing and then take a caulking tube full of silicone glue and pump it into the void between the axle and the housing. Keep the hub as close to the housing as you can till you get the silicone pumped in.Use the whole tube and then replace the axle into the housing and replace the bolts etc. Let the silicone cure overnight and then you can go about using the tractor. Be sure that the oil in the rearend etc is not over full as this will contribute to the axle leaking.

Loosen but do not remove the nuts holding the wheel. Use a 4x4 or 4x6 & place against the inside of the opposite wheel. Place a jack between the 4x4 & the wheel to be removed and apply steady pressure with the jack. When it finally breaks loose, the wheel may eject from the tractor, so be sure the nuts are in place because that sucker is heavy! I am sure there are other ways but this method works.