I've narrowed many rear ends. The place to start is with the tires mounted on the wheels that you want to run. Put them under the car with no rear end in it. Get them in exactly the location that you want them to run and then measure the distance between the mounting surfaces. This will be your total rear end width including the brakes.
__________________
Freddie
1969 Camaro RS/SS396 (427) 4 speed
|