8 1/4 LBP Rear End in a 68 Valiant
You should be able to use anything from 1967 up to a 1976 Dart or Duster in your 68 but for LBP it should be 73 and up. I took the whole driveline from a 1974 Valiant and put it in my 68 Valiant and it bolted right in. Any A body parts should drop in. Volares are F body.