My son and I both have Chevelles. On my 66 I used the 70 Chevelle rotors Brackets etc with a wildwood adj. valve and a non power dual master cylinder. On the front I used 3/16 line and in the rear I ran new 1/4 line to the rear brakes. We are in the process of doing the same to my son's 65 and he also has 3/16 line in the front but also in the back. Were a 65 and 66 different sizes of line going to the rear brakes or did I go to a larger size when I changed the line? Could it be that because his was power the line was smaller? What have You guy's used in the front and back?