2006 R/T

My Charger has to be one of the rarest. In reading these forums, I am shocked at how many problems this car is suppose to have. Nothing major until now has gone wrong. The rear end needs to be replaced. I have 145,000 miles on it and I drive it like a bat.... and semi-race on the interstate, but not around traffic. I am NOT a mechanic. My father was so I know a little about cars, but I can't fix them myself like most of you guys. My mechanic told me it would cost $4,000 to replace the rear end. I guess that would be new??? and he would charge $800 to install it. A few days later he told me he couldn't find one or even parts. He has never been out of line with pricing and has always done a great job but that doesn't sound right. I called the Dealer (I know, a no no) they told me that Dodge doesn't even make them anymore or their parts for the old chargers!! I found a few wrecking yards but you have to pull the parts yourself and then you don't know if it's going to work. I contacted a guy here in TX that only works on Chargers and he said he doesn't work on the 2006 and never will - hates them. Wow! This car to me is worth a million bucks but to sell it, especially in this condition, I don't think I could even get $2,000 for it, even for parts. This car has stuff on it like you can't believe. Fully loaded. It would be a gold mine for parts. I said all that to ask this - Is it true there are no parts but wrecking yard parts? Does it really cost that much to replace the rear end? Do I just need to let it go? I hope someone has some positive information. Thanks.