Ok, that last digit is a 9. Although, there was a 488 case, too, it was the same physically as the 489, so both cases are referred to as the 489, since the 489 was MUCH more prolific. Well, I WAS gonna say to maybe just give the pinion nut a few pops with a 1/2" drive impact.....and you still can, but do it CAREFULLY, because that has a crush sleeve. But I'd drop the drive shaft and check for any movement first and report back......and you know what? If there's no excessive play, I'll be damned if I wouldn't leave it alone. That noise is very faint.
