The only auto OD would be the either a LA 42RH or a Chevy (forget the nomenclature) BUT to mate either to a slant, an adapter would be needsd. For example a slant to LA, an adapter was used64 to 66. Over at slant6.org there was a group buy on the Chevy to slant adapter. I’m using a 42RH in my 65 Dart but it will be mated to a 273. There are other consideration to used one of those OD’s