You`ll really need to ID your gear ratio first, top right side of diff housing will have the id number, it could be 373 / 410 or 342 /331 if its original one of those four, it could even have a later 308 if someone else has changed it over the years, i`m still running stock drums, if you choose drums go with the later 67-72 6 or five lug, on all four corners they are a little larger, you`ll have less brake fade, Early classic chevy or Cpp has all the disc brake change over or just change out the complete front cross member with everything attached will bolt right up to your frame, you just have to drill two new holes, from `66 to `86 will work, you`ll also need to grab master cyl, power booster lines proportioning valve, or get a complete donor truck.