Disc options for 73-76 drum spindle???

Hmmm, interesting kit, but I wonder why they use truck discs and a spindle/bearing adaptor? Aren't the later B body rotors a straight fit on to these spindles? The AR kit looked better, but Viper calipers aren't cheap either, any other ideas?

IIRC the truck rotors are used because the thickness is within the Viper rotor's operating clamping range. If you use the 1" rotors, those pads may not contact the rotors.