Rotor/Brake/Spindle/caliper Mismatch - need help

[reb162]

I have a 1971 Chevrolet C-10 that I am installing an ECE 4/6 Drop kit on. I have the spindles on and ordered new rotors, brakes and calipers.

The original rotors were 1.25 thick and so are the new ones. I put the rotors on the spindles and all seems to fit well until I go to install the caliper with the new brake pads....the fit is too tight even if remove the pad shims.

After some investigation, it appears the calipers I ordered from Rock Auto are about a .25" thinner than my old ones...so probably meant for the thinner rotor. They were GM refurbished but had a note that said "to 4/71". I'm guessing I need the wider calipers...how do I know I'm getting the wider calipers? Did GM change to the wider ones after 4/71?

That got me to thinking, maybe the ECE drop spindles are not designed for the 1.25" thick rotor, but for the 1" rotor. Anyone know?

What the best way out of this...I'm outside the return window on any of this stuff so I'm eating the cost of something.

Thanks