How do I choose a rear

[paulk68]

I am building a 68 camaro that has been mini tubbed and I have the ridetch 4 link to bolt in place. I am thinking of going with a moser 12 bolt much like the 48 hour camaro build. do i need to take specific measurements to place the order f0r the rear? or can i just tell them i need a shortened rear to fit the minitubs? I will be going with 18" wheels and Baer brakes. Also I am thinking i will be safe with 3:73 gears. I plan to run a t-56 with around 550 hp. Any help woul dbe much appreciated
Thanks