Nissan Repair: Titan, Rear end went out

Question
QUESTION: I was pulling out of the gas station and hit the rumble strip a bit, I heard a loud POP and suddenly my truck wouldn't go. I put it in four wheel drive and made the very slow 2 miles drive home. I figured the rear end went out or the axel broke but to be honest I know very little about vehicles, just enough to get me by.
I was curious as to what it sounded like to you. Do you know what could be wrong with my truck? And what parts I will need to fix it? Also, if you happen to know, off the top of your head, how much it will cost me that would be wonderful!  I don't want you to have to do any price checking or shopping for me, so if you can't give me a price estimation that it fine and completely understandable.
Thank you in advance for all your time and advice. It is greatly appreciated.
Have a good day.

Blandy

ANSWER: Hi Blandy -

If you could I need more info. I wish I was there to check it out but obviously not, so please bear with me.

Is your Titan manual or automatic transmission?

When you put it in gear and try to go forward, are there any noises besides the engine revving up?

Does it work in reverse?

If you have automatic transmission, how is the trans oil level and when you pull the dipstick, any metal flakes in the oil?

LMK

aloha
Calvin

---------- FOLLOW-UP ----------

QUESTION: Ask away, I need all the help I can get.
I guess I should of mentioned it is a 2005 v8, automatic with an off road package and with a rear locking differential.
It will not go forward without being put in 4 wheel high. It will go in reverse though. I took the cover off the rear end and there are some big chucks of metal and lots of metal dust/ flakes but the gears I can see look fine. No teeth missing, not worn down, nothing like that. I tried spinning the tires and when you spin one the other does not move and the passenger side rear tire wiggles if you shake it a bit while the drivers side does not.
If you need anymore info just let me know, I will do my best to answer.

Thank you so much for your time and patience.
Blandy

Answer
Hi Blandy -

It appears that one or more of the differential gears went out. There are several gears in there including a ring gear, pinion gear, spider gears, side gears, etc., as well as some bearings. My guess is the pinion gear, as that one is not really visible when you remove the cover.

The reason why it works in 4 wheel drive is because the front wheels are the drive wheels instead of the rear, comes from the transfer case.

So in summary you will need to replace the differential of your vehicle. My guess would be $800 to fix.

Hope this helps -
aloha
Calvin