I have seen these on ebay in two different lengths. I have a 72 cuda 742 case and have considered finding one. How long should it be?

Thanks

1972 Cuda 340 4 speed, 2001 Ram CTD 4x4 6 speed, 1970 Duster 408 4 speed, 1996 Ram 5.9 2x4 auto, 1965 Coronet 500