Having exploded a number of these over the years, you hear a loud bang and roll to a stop.....
If you dont like walking home, clean fluid (75/90) helps a lot. Late in the life of an old diff,
they shed teeth from the pinion. You notice this when ,in reverse, it stops suddenly as a tooth
jambs the ring gear. For a while it will work more or less normally , then BANG!!!
Mad dog