Supposedly the factory spaced the k-frame down from the frame with spacers (i think 1/2") then raised the engine up with spacers to make more room for exhaust/steering...
this is from a original car owner
"the hemi darts used a B-body type hemi mount, what that did is put the engine exactly where mine is "the stock location" but lowered the K-frame by the amount of the spacer. what that does is give you more clearence between the engine and the steering linkage"