There is one difference in a 1970 and later 8 3/4" versus the pre-70 unit! In 1970 the distribution block and vent was moved from the bottoms edge of where the hump starts to a little further down the drivers side axle tube! This results in needing to order the correct set of lines, and may also necessitate getting a longer rubber hose, depending on which car it's coming out of or going into!! Other than that, same same!!
