Weird Hemi Header set up

Those T-bolt 180 headers combine the cylinders in order so there is no thump thump thump like a V8 but more of a 4cyl or motorcycle tone out of each side. My B2000 has a factory 2 Y 1-4,2-3 cast iron header manifold that feeds a double pipe to a collector, pretty strange for a lo-po 1976cc torque motor. There must have been something in pairing cylinders like that even on the hemi.