Ricks Road Runner automatically gets the 8 3/4 rear if it is a hemi/torqueflite car. They did not offer a Super track pack option until 1969 where you could get a dana with a automatic. All hemi torqueflites came with 8 3/4 from 1968 and earlier. Dana with hemi 4 speed. That extra weight may give another .05- .10 in the quarter mile
-------------------- RM27H9G 4 speed F8/tan guts RS27L9G auto B5/black guts WM23H9G auto F5/green guts 2021 Challenger 392 Indigo/black guts 2019 Charger Daytona R/T F8 on black 2018 Ram Sport Hemi 4x4