I don't know about availability over in the States,but a junkyard contender might be a Jaguar back axle.It's an IRS unit with loads of diff options and as tuff as old boots!
It would certainly be man enough and can be made to look good too!.
It's quite a common swap over here. Guys use them in loads of different cars/vans etc.
You should be pretty close to the correct width too.
Just my 2c.
