The DS (40-45) basically uses the complete old DK 40 tractor except the front axle is the same as the DK SE series.
They use a straight gear trans, pretty much the same as the old DK only without synchronizers on the shuttle or main trans.
There are niceties removed like the suspension seat, remote hydraulics, tilt steering wheel, pin style sway bar links and extendable 3pt arms.
They changed the front end "body" and grill and made it so everything for maintenance could be reached from one side.
The PTO is also on or off with no "automatic" setting.
The machines are simple and pretty much bullet-proof
Your assumption on HP is correct.
BTI