Chosen Solution
a leake from the axel on brakes
If you sniff it n almost barf, its an axle seal (gear oil smells nasty). If its kind of slick, but not as viscous as motor oil, its brake fluid, and therefore wheel cylinder in the rear brake. https://m.youtube.com/watch?v=sWhfvTfvCG… https://m.youtube.com/watch?v=5KsYKwtFTl…
Axle bearing has failed, This is always first case of any axle gear oil to escape. And Yes, it is nasty rank smell, Now get it hot enough to smoke from using brakes,, as a default,,, gear oil soaked brake shoes will tend to lock up the rear wheel even light pressure of brakes. The brake shoes can be salvaged,,, but they will need To soak in high grade solvent,, typically Naptha in first phase,, then brake cleaner for final phase. But if local source has them cheap, simply replace,, As Farmers,, we tend to give stuff a second chance regardless. Best of Luck Quick note, typical throw away axles need to have bearings Pressed On. But not impossible with clever tooling. Quick note 2: If axle is too damaged at seal area, There is option for offset bearing To allow seal to get new surface, Also speedy sleeve is 3rd option to salvage seal zone. Quick note 3 This would be great time to flush out rear end and upgrade the oil.