If I got everything properly, then the following was the KBB Results.
FAIR: $6,186 - $9,267
GOOD: $7,108 - $10,257
So you're right around that range with what you think it's worth. FAIR is going to be the lowest value based on the damage on the front bumper. This was priced with a standard package.
IF the diff was already rebuilt, then you should be set for a while - depending on what they rebuilt it with.
What are your plans on mods?