Back in the 80's I got a good deal like that once.
One of the local junk yards had a duster with an 8 3/4 rear. He wanted $75 for it, then I also wanted the drive shaft from the car. He wanted $10 more for the drive shaft. When I paid him the extra for the axle, he gave me the wrong "change" back. Instead of paying $85 for the two, I ended up paying only $65 for the axle and drive shaft.
Many years later my brother discovered that it was also a sure grip.... BONUS!!!!