hijacked_sign.gif I think it may be the angle, but they may be crooked to the housing. This is not important. What is important is that the calipers line up square to the rotors.
The way I did this was to install the un-welded brackets on the calipers with pads installed. Then bolt the rotors down on the axle flanges and slip the calipers and brackets over the rotor clocked exactly where you want them. Use an air compressor to shoot air into the brake line inlets in the calipers. This compresses the caliper on the rotor square. Hold the air to it and weld the brackets into place.
FYI, It will amaze you how out of square everything is to the housing itself. That is why a rear end jig is a must for this project. Everything lines up off the carrier bearings inside the housing this way. Axle tubes are very rarely straight with the carrier.