Hi Ls not totally sure but I think it is along the lines of modernization equaling miniaturization. Remembering back to early 80's the smaller sized unit solved or helped heaps with exhaust extractor clearance dramas on my HQ. The smaller modulator had a tiny screw inside accessed thru the vaccum port to adjust gearshift points slightly (earlier or later ) Remember clearly laying in the dirt on the roadside burning my arm whilst turning the screw to get a more desirable shift from the old low compression beast.