Since you have a 65 Dart (great choice BTW!), any 63-76 A Body rear end - 7.25/8.25 or 8.75 - is a bolt in. The 7.25 and 8.75 use the SBP 5 on 4 wheels the same as what you currently have. The A Body 8.25 (73-76) uses LBP 4.5 on 5. Hope this helps a bit.